diff --git a/modules/planning/common/BUILD b/modules/planning/common/BUILD
index ec572f817455ec780a242ee29cee94bae9be8bad..0f02c56eee7c2f0a66664ab3b290cd6a2f2a4afb 100644
--- a/modules/planning/common/BUILD
+++ b/modules/planning/common/BUILD
@@ -98,6 +98,7 @@ cc_library(
     deps = [
         ":indexed_list",
         ":obstacle",
+        "//modules/planning/common/speed:st_boundary",
         "//modules/planning/proto:planning_proto",
         "//modules/planning/reference_line",
     ],
diff --git a/modules/planning/common/path_obstacle.cc b/modules/planning/common/path_obstacle.cc
index 8c6aeee705408cb1ba37bc86f54bc9f449676c6a..b366f10211588647291af5483751d3ee50cffa35 100644
--- a/modules/planning/common/path_obstacle.cc
+++ b/modules/planning/common/path_obstacle.cc
@@ -55,6 +55,13 @@ bool PathObstacle::Init(const ReferenceLine& reference_line) {
     AERROR << "Failed to get sl boundary for obstacle: " << id_;
     return false;
   }
+  if (!BuildStBoundary(reference_line, obstacle_)) {
+  }
+  return true;
+}
+
+bool PathObstacle::BuildStBoundary(const ReferenceLine& reference_line,
+                                   const Obstacle* obstacle) {
   return true;
 }
 
diff --git a/modules/planning/common/path_obstacle.h b/modules/planning/common/path_obstacle.h
index 9556d7dbc914e9225d43c7d3dde5aa9c97f8121b..e073882e2bea7072d80b450b12c893e0c520ece8 100644
--- a/modules/planning/common/path_obstacle.h
+++ b/modules/planning/common/path_obstacle.h
@@ -37,6 +37,7 @@
 #include "modules/common/math/vec2d.h"
 #include "modules/planning/common/indexed_list.h"
 #include "modules/planning/common/obstacle.h"
+#include "modules/planning/common/speed/st_boundary.h"
 #include "modules/planning/reference_line/reference_line.h"
 
 namespace apollo {
@@ -123,14 +124,16 @@ class PathObstacle {
   static ObjectDecisionType MergeLateralDecision(const ObjectDecisionType& lhs,
                                                  const ObjectDecisionType& rhs);
 
+  bool BuildStBoundary(const ReferenceLine& reference_line,
+                       const Obstacle* obstacle);
+
   std::string id_;
   const Obstacle* obstacle_ = nullptr;
   std::vector<ObjectDecisionType> decisions_;
   std::vector<std::string> decider_tags_;
   SLBoundary perception_sl_boundary_;
 
-  // TODO(zhangliangliang): add st_boundary_ here.
-  // StBoundary st_boundary_;
+  StBoundary st_boundary_;
 
   ObjectDecisionType lateral_decision_;
   ObjectDecisionType longitudinal_decision_;
diff --git a/modules/planning/common/speed/BUILD b/modules/planning/common/speed/BUILD
index 781606c86e83c1be21c5c19d47219ba4c833e52b..3b427bf9ca8a411a7c082d284b7fe502f0757a83 100644
--- a/modules/planning/common/speed/BUILD
+++ b/modules/planning/common/speed/BUILD
@@ -17,6 +17,36 @@ cc_library(
     ],
 )
 
+cc_library(
+    name = "st_boundary",
+    srcs = [
+        "st_boundary.cc",
+    ],
+    hdrs = [
+        "st_boundary.h",
+    ],
+    deps = [
+        ":st_point",
+        "//modules/common:log",
+        "//modules/planning/proto:planning_proto",
+    ],
+)
+
+cc_test(
+    name = "st_boundary_test",
+    size = "small",
+    srcs = [
+        "st_boundary_test.cc",
+    ],
+    deps = [
+        ":st_boundary",
+        "//modules/common:log",
+        "//modules/common/time",
+        "//modules/common/util",
+        "@gtest//:main",
+    ],
+)
+
 cc_library(
     name = "speed_data",
     srcs = [
diff --git a/modules/planning/tasks/st_graph/st_boundary.cc b/modules/planning/common/speed/st_boundary.cc
similarity index 98%
rename from modules/planning/tasks/st_graph/st_boundary.cc
rename to modules/planning/common/speed/st_boundary.cc
index d8273c94c5ae4cd4e00a2163b3ffd6ee9e2193af..2cb425397afbd67717169d21bdd89a162af9e625 100644
--- a/modules/planning/tasks/st_graph/st_boundary.cc
+++ b/modules/planning/common/speed/st_boundary.cc
@@ -18,7 +18,7 @@
   * @file
   **/
 
-#include "modules/planning/tasks/st_graph/st_boundary.h"
+#include "modules/planning/common/speed/st_boundary.h"
 
 #include <algorithm>
 
diff --git a/modules/planning/tasks/st_graph/st_boundary.h b/modules/planning/common/speed/st_boundary.h
similarity index 100%
rename from modules/planning/tasks/st_graph/st_boundary.h
rename to modules/planning/common/speed/st_boundary.h
diff --git a/modules/planning/tasks/st_graph/st_boundary_test.cc b/modules/planning/common/speed/st_boundary_test.cc
similarity index 97%
rename from modules/planning/tasks/st_graph/st_boundary_test.cc
rename to modules/planning/common/speed/st_boundary_test.cc
index 6fc7f2a01b15b560ff3ebf350f57cd9e1e76114e..cc522d28cc4b7dd4c395339e90bcf7802ebe6aa3 100644
--- a/modules/planning/tasks/st_graph/st_boundary_test.cc
+++ b/modules/planning/common/speed/st_boundary_test.cc
@@ -14,7 +14,7 @@
  * limitations under the License.
  *****************************************************************************/
 
-#include "modules/planning/tasks/st_graph/st_boundary.h"
+#include "modules/planning/common/speed/st_boundary.h"
 
 #include <algorithm>
 #include <cmath>
diff --git a/modules/planning/tasks/BUILD b/modules/planning/tasks/BUILD
index 45b2cd06c6c42223cdf2d9361de2a3a7beecd8f8..514bd8e44d26f5fff18e6fbf0ab285d426fdafea 100644
--- a/modules/planning/tasks/BUILD
+++ b/modules/planning/tasks/BUILD
@@ -55,7 +55,7 @@ cc_library(
         "//modules/planning/common:speed_limit",
         "//modules/planning/common/path:path_data",
         "//modules/planning/common/speed:speed_data",
-        "//modules/planning/tasks/st_graph:st_boundary",
+        "//modules/planning/common/speed:st_boundary",
         "@eigen//:eigen",
     ],
 )
diff --git a/modules/planning/tasks/dp_st_speed/BUILD b/modules/planning/tasks/dp_st_speed/BUILD
index 6fb21a3b75124ac2b995073ec477f31a5a2440f3..56f53106e0546707e9438f91b57f382f6ae1cc2c 100644
--- a/modules/planning/tasks/dp_st_speed/BUILD
+++ b/modules/planning/tasks/dp_st_speed/BUILD
@@ -27,9 +27,9 @@ cc_library(
     deps = [
         "//modules/common/proto:pnc_point_proto",
         "//modules/planning/common:frame",
+        "//modules/planning/common/speed:st_boundary",
         "//modules/planning/math:double",
         "//modules/planning/proto:dp_st_speed_config_proto",
-        "//modules/planning/tasks/st_graph:st_boundary",
     ],
 )
 
diff --git a/modules/planning/tasks/dp_st_speed/dp_st_cost.h b/modules/planning/tasks/dp_st_speed/dp_st_cost.h
index 762fd6c2351fcfc9558b14462f1c95c619616d34..2f1be8878d2a0e1a3c58d36c8a988cf9c9d2c4d1 100644
--- a/modules/planning/tasks/dp_st_speed/dp_st_cost.h
+++ b/modules/planning/tasks/dp_st_speed/dp_st_cost.h
@@ -27,7 +27,7 @@
 #include "modules/planning/proto/dp_st_speed_config.pb.h"
 
 #include "modules/planning/common/speed/st_point.h"
-#include "modules/planning/tasks/st_graph/st_boundary.h"
+#include "modules/planning/common/speed/st_boundary.h"
 
 namespace apollo {
 namespace planning {
diff --git a/modules/planning/tasks/qp_spline_st_speed/qp_spline_st_graph.h b/modules/planning/tasks/qp_spline_st_speed/qp_spline_st_graph.h
index 0c028e9a8270cd90d3b039d72da126fce4d57162..df8ef15c6aa439aed714891d8934f4b2384f111e 100644
--- a/modules/planning/tasks/qp_spline_st_speed/qp_spline_st_graph.h
+++ b/modules/planning/tasks/qp_spline_st_speed/qp_spline_st_graph.h
@@ -34,7 +34,7 @@
 #include "modules/planning/common/planning_util.h"
 #include "modules/planning/common/speed/speed_data.h"
 #include "modules/planning/math/smoothing_spline/spline_1d_generator.h"
-#include "modules/planning/tasks/st_graph/st_boundary.h"
+#include "modules/planning/common/speed/st_boundary.h"
 #include "modules/planning/tasks/st_graph/st_graph_data.h"
 
 namespace apollo {
diff --git a/modules/planning/tasks/speed_optimizer.h b/modules/planning/tasks/speed_optimizer.h
index c47e539ae676d82a188a9595456f9b077d702a07..9103a5ef92f5644dd9c94cf3888f6c736e0ae45e 100644
--- a/modules/planning/tasks/speed_optimizer.h
+++ b/modules/planning/tasks/speed_optimizer.h
@@ -27,7 +27,7 @@
 #include "modules/common/status/status.h"
 #include "modules/planning/common/speed/speed_data.h"
 #include "modules/planning/common/speed_limit.h"
-#include "modules/planning/tasks/st_graph/st_boundary.h"
+#include "modules/planning/common/speed/st_boundary.h"
 #include "modules/planning/tasks/task.h"
 
 namespace apollo {
diff --git a/modules/planning/tasks/st_graph/BUILD b/modules/planning/tasks/st_graph/BUILD
index 67bed2248369af4eed13767b8b696a721d8538e1..3560cdd30772411f2e6f103c97d9f1816056abda 100644
--- a/modules/planning/tasks/st_graph/BUILD
+++ b/modules/planning/tasks/st_graph/BUILD
@@ -2,22 +2,6 @@ load("//tools:cpplint.bzl", "cpplint")
 
 package(default_visibility = ["//visibility:public"])
 
-cc_library(
-    name = "st_boundary",
-    srcs = [
-        "st_boundary.cc",
-    ],
-    hdrs = [
-        "st_boundary.h",
-    ],
-    deps = [
-        "//modules/common:log",
-        "//modules/common/math",
-        "//modules/planning/common/speed:st_point",
-        "//modules/planning/proto:planning_proto",
-    ],
-)
-
 cc_library(
     name = "st_graph_data",
     srcs = [
@@ -27,9 +11,9 @@ cc_library(
         "st_graph_data.h",
     ],
     deps = [
-        ":st_boundary",
         "//modules/planning/common:planning_gflags",
         "//modules/planning/common:speed_limit",
+        "//modules/planning/common/speed:st_boundary",
     ],
 )
 
@@ -42,7 +26,6 @@ cc_library(
         "st_boundary_mapper.h",
     ],
     deps = [
-        ":st_boundary",
         "//modules/common/configs:vehicle_config_helper",
         "//modules/common/configs/proto:vehicle_config_proto",
         "//modules/common/proto:pnc_point_proto",
@@ -57,6 +40,7 @@ cc_library(
         "//modules/planning/common/path:discretized_path",
         "//modules/planning/common/path:frenet_frame_path",
         "//modules/planning/common/path:path_data",
+        "//modules/planning/common/speed:st_boundary",
         "//modules/planning/common/trajectory:discretized_trajectory",
         "//modules/planning/math:double",
         "//modules/planning/proto:planning_proto",
@@ -83,21 +67,6 @@ cc_test(
     ],
 )
 
-cc_test(
-    name = "st_boundary_test",
-    size = "small",
-    srcs = [
-        "st_boundary_test.cc",
-    ],
-    deps = [
-        ":st_boundary",
-        "//modules/common:log",
-        "//modules/common/time",
-        "//modules/common/util",
-        "@gtest//:main",
-    ],
-)
-
 cc_test(
     name = "st_graph_data_test",
     size = "small",
@@ -105,7 +74,6 @@ cc_test(
         "st_graph_data_test.cc",
     ],
     deps = [
-        ":st_boundary",
         ":st_graph_data",
         "//modules/common:log",
         "//modules/common/time",
diff --git a/modules/planning/tasks/st_graph/st_boundary_mapper.h b/modules/planning/tasks/st_graph/st_boundary_mapper.h
index 6c34dfca18e65efa1ea5fa304d8746fe7c19f113..8e669e4faed6611320effe80e24220d12d47f3db 100644
--- a/modules/planning/tasks/st_graph/st_boundary_mapper.h
+++ b/modules/planning/tasks/st_graph/st_boundary_mapper.h
@@ -31,7 +31,7 @@
 #include "modules/planning/common/path_decision.h"
 #include "modules/planning/common/speed_limit.h"
 #include "modules/planning/reference_line/reference_line.h"
-#include "modules/planning/tasks/st_graph/st_boundary.h"
+#include "modules/planning/common/speed/st_boundary.h"
 
 namespace apollo {
 namespace planning {
diff --git a/modules/planning/tasks/st_graph/st_graph_data.h b/modules/planning/tasks/st_graph/st_graph_data.h
index 71f4ba83d148b5646deb77244cb624baebd05e47..fdcecbcb0785a8e20cfe5a3b9d7d3461721b17bb 100644
--- a/modules/planning/tasks/st_graph/st_graph_data.h
+++ b/modules/planning/tasks/st_graph/st_graph_data.h
@@ -27,7 +27,7 @@
 #include "modules/common/proto/pnc_point.pb.h"
 
 #include "modules/planning/common/speed_limit.h"
-#include "modules/planning/tasks/st_graph/st_boundary.h"
+#include "modules/planning/common/speed/st_boundary.h"
 
 namespace apollo {
 namespace planning {
diff --git a/modules/planning/tasks/st_graph/st_graph_data_test.cc b/modules/planning/tasks/st_graph/st_graph_data_test.cc
index a6bbb520bc4fba3efc626bfd51de4540224248e2..04cb56a93cb3321f9dc8336a60a2cbb0532b53cf 100644
--- a/modules/planning/tasks/st_graph/st_graph_data_test.cc
+++ b/modules/planning/tasks/st_graph/st_graph_data_test.cc
@@ -23,7 +23,7 @@
 #include "gtest/gtest.h"
 
 #include "modules/common/log.h"
-#include "modules/planning/tasks/st_graph/st_boundary.h"
+#include "modules/planning/common/speed/st_boundary.h"
 
 namespace apollo {
 namespace planning {