diff --git a/CMakeLists.txt b/CMakeLists.txt
index d7f063e4689bfc7022f087d81003d47c342135dc..24b7118964d40bb9427de0c3f687f1523476900a 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,8 +1,9 @@
 cmake_minimum_required(VERSION 3.6)
+option(USE_OPENMP "openmp support" ON)
+
 project(paddle-mobile)
 
 option(DEBUGING "enable debug mode" OFF)
-option(USE_OPENMP "openmp support" OFF)
 option(USE_EXCEPTION "use std exception" OFF)
 option(LOG_PROFILE "log profile" OFF)
 # select the platform to build
diff --git a/src/ios_io/PaddleMobile.mm b/src/ios_io/PaddleMobile.mm
index 9298e7907709bbbed77b3d4d76528689cae7bd93..5c7b801be0ea7967ea0c94813325d41071bb890b 100644
--- a/src/ios_io/PaddleMobile.mm
+++ b/src/ios_io/PaddleMobile.mm
@@ -58,6 +58,7 @@ static std::mutex shared_mutex;
 - (BOOL)load:(NSString *)modelPath andWeightsPath:(NSString *)weighsPath{
   std::string model_path_str = std::string([modelPath UTF8String]);
   std::string weights_path_str = std::string([weighsPath UTF8String]);
+  pam_->SetThreadNum(2);
   if (loaded_ = pam_->Load(model_path_str, weights_path_str, true)) {
     return YES;
   } else {
diff --git a/tools/ios-cmake/ios.toolchain.cmake b/tools/ios-cmake/ios.toolchain.cmake
index 4db079d01de8db35fca8fbe63b59e58fd5a3463e..6000f7a8e5dffcd8693b56539f4519840ddd8be8 100644
--- a/tools/ios-cmake/ios.toolchain.cmake
+++ b/tools/ios-cmake/ios.toolchain.cmake
@@ -50,8 +50,13 @@ endif (CMAKE_UNAME)
 #include (CMakeForceCompiler)
 #CMAKE_C_COMPILER (/usr/bin/gcc)
 #CMAKE_CXX_COMPILER (/usr/bin/g++)
-set(CMAKE_C_COMPILER /usr/bin/gcc)
-set(CMAKE_CXX_COMPILER /usr/bin/g++)
+if(USE_OPENMP)
+    set(CMAKE_C_COMPILER /usr/local/opt/llvm/bin/clang)
+    set(CMAKE_CXX_COMPILER /usr/local/opt/llvm/bin/clang++)
+else()
+    set(CMAKE_C_COMPILER /usr/bin/gcc)
+    set(CMAKE_CXX_COMPILER /usr/bin/g++)
+endif()
 set(CMAKE_AR ar CACHE FILEPATH "" FORCE)
 
 # Skip the platform compiler checks for cross compiling