diff --git a/docs/CHANGELOG.md b/docs/CHANGELOG.md
index 1669752f..a84beb29 100644
--- a/docs/CHANGELOG.md
+++ b/docs/CHANGELOG.md
@@ -9,6 +9,10 @@
 - refactor: build plugin mechanism
 - fix: pip upgrade httprunner when installing hrp
 
+**python version**
+
+fix: unexpected changes in step variables
+
 ## v4.1.2 (2022-06-09)
 
 - feat: add Dockerfile
diff --git a/hrp/internal/builtin/utils.go b/hrp/internal/builtin/utils.go
index fe702f97..9f6d2b92 100644
--- a/hrp/internal/builtin/utils.go
+++ b/hrp/internal/builtin/utils.go
@@ -92,13 +92,14 @@ func FormatResponse(raw interface{}) interface{} {
 var Python3Executable string = "python3" // system default python3
 
 func PrepareVenv(venv string) error {
-	defer func() {
-		log.Info().Str("Python3Executable", Python3Executable).Msg("set python3 executable path")
-	}()
-
 	// specify python3 venv
 	if venv != "" {
-		Python3Executable = getPython3Executable(venv)
+		python3 := getPython3Executable(venv)
+		if !IsFilePathExists(python3) {
+			return errors.New("specified python3 venv is invalid")
+		}
+		Python3Executable = python3
+		log.Info().Str("Python3Executable", Python3Executable).Msg("set python3 executable path")
 		return nil
 	}
 
@@ -108,7 +109,7 @@ func PrepareVenv(venv string) error {
 		return errors.Wrap(err, "create default python3 venv failed")
 	}
 	Python3Executable = python3
-
+	log.Info().Str("Python3Executable", Python3Executable).Msg("set python3 executable path")
 	return nil
 }