diff --git a/src/client/src/tscFunctionImpl.c b/src/client/src/tscFunctionImpl.c
index 07aa94d0b381025a6350c05dc17f18e5026eb6c4..15432e7040a90689ee44cf598fae66bf0f27bcc1 100644
--- a/src/client/src/tscFunctionImpl.c
+++ b/src/client/src/tscFunctionImpl.c
@@ -3658,7 +3658,7 @@ static double twa_get_area(SPoint1 s, SPoint1 e) {
     return (s.val + e.val) * (e.key - s.key) / 2;
   }
 
-  double x = (s.val - s.key) * e.key / (s.val - e.key);
+  double x = (s.key * e.val - e.key * s.val)/(e.val - s.val);
   double val = (s.val * (x - s.key) + e.val * (e.key - x)) / 2;
   return val;
 }
diff --git a/tests/script/general/parser/function.sim b/tests/script/general/parser/function.sim
index 79c620f90d06f1131c45d1705dccd5e5b311585e..3505ad1a28139a85e62193eddeb050dfde0bbc0d 100644
--- a/tests/script/general/parser/function.sim
+++ b/tests/script/general/parser/function.sim
@@ -22,7 +22,7 @@ $db = $dbPrefix . $i
 $mt = $mtPrefix . $i
 
 sql drop database if exists $db
-sql create database $db
+sql create database $db keep 36500
 sql use $db
 
 print =====================================> test case for twa in single block
@@ -231,3 +231,16 @@ sql select twa(k),avg(k),count(1) from t1 where ts>='2015-8-18 00:00:00' and ts<
 #todo add test case while column filter exists.
 
 #sql select count(*),TWA(k) from tm0 where ts>='1970-1-1 13:43:00' and ts<='1970-1-1 13:44:10' interval(9s)
+
+sql create table tm0 (ts timestamp, k float);
+sql insert into tm0 values(100000000, 5);
+sql insert into tm0 values(100003000, -9);
+sql select twa(k) from tm0 where ts<now
+if $rows != 1 then
+  return -1
+endi
+
+if $data00 != -2.000000000 then
+  print expect -2.000000000, actual: $data00
+  return -1
+endi