diff --git a/pkg/project/project.go b/pkg/project/project.go
index 4408970d..ad92bfad 100644
--- a/pkg/project/project.go
+++ b/pkg/project/project.go
@@ -188,7 +188,7 @@ func (f *project) dealVarsFiles(p *kkprojectv1.Play, basePlaybook string) error
 		// combine map node
 		if node.Content[0].Kind == yaml.MappingNode {
 			// skip empty file
-			p.Vars = *variable.CombineMappingNode(node.Content[0], &p.Vars)
+			p.Vars = *variable.CombineMappingNode(&p.Vars, node.Content[0])
 		}
 	}
 
@@ -234,7 +234,7 @@ func (f *project) dealRoles(p kkprojectv1.Play, basePlaybook string) error {
 			// combine map node
 			if node.Content[0].Kind == yaml.MappingNode {
 				// skip empty file
-				p.Roles[i].Vars = *variable.CombineMappingNode(node.Content[0], &p.Roles[i].Vars)
+				p.Roles[i].Vars = *variable.CombineMappingNode(&p.Roles[i].Vars, node.Content[0])
 			}
 		}
 	}
diff --git a/pkg/variable/helper.go b/pkg/variable/helper.go
index 8a56bfba..c5c33018 100644
--- a/pkg/variable/helper.go
+++ b/pkg/variable/helper.go
@@ -37,9 +37,9 @@ import (
 )
 
 // CombineMappingNode combines two yaml.Node objects representing mapping nodes.
-// If b is nil or zero, returns a.
-// If both a and b are mapping nodes, appends a's content to b.
-// Returns b in all other cases.
+// If a is nil or zero, returns b.
+// If both a and b are mapping nodes, appends b's content to a.
+// Returns a in all other cases.
 //
 // Parameters:
 //   - a: First yaml.Node to combine
@@ -48,15 +48,15 @@ import (
 // Returns:
 //   - Combined yaml.Node, with b taking precedence
 func CombineMappingNode(a, b *yaml.Node) *yaml.Node {
-	if b == nil || b.IsZero() {
-		return a
+	if a == nil || a.IsZero() {
+		return b
 	}
 
 	if a.Kind == yaml.MappingNode && b.Kind == yaml.MappingNode {
-		b.Content = append(b.Content, a.Content...)
+		a.Content = append(a.Content, b.Content...)
 	}
 
-	return b
+	return a
 }
 
 // CombineVariables merge multiple variables into one variable.
diff --git a/pkg/variable/yaml.go b/pkg/variable/yaml.go
index 51713292..d4c4c870 100644
--- a/pkg/variable/yaml.go
+++ b/pkg/variable/yaml.go
@@ -176,6 +176,10 @@ func handleMap(current reflect.Value, key string, isLast bool, value any,
 	rKey := reflect.ValueOf(key)
 	existing := current.MapIndex(rKey)
 	if isLast {
+		if existing.IsValid() && !isNil(existing) {
+			// skip
+			return current, nil
+		}
 		if value == nil {
 			current.SetMapIndex(rKey, reflect.Zero(reflect.TypeOf((*any)(nil)).Elem()))
 		} else {
@@ -229,6 +233,11 @@ func handleSlice(current reflect.Value, val string, isLast bool, value any,
 	}
 	// Handle setting the final value
 	if isLast {
+		existingItem := current.Index(index)
+		if existingItem.IsValid() && !isNil(existingItem) {
+			// skip
+			return current, nil
+		}
 		if value == nil {
 			current.Index(index).Set(reflect.Zero(reflect.TypeOf((*any)(nil)).Elem()))
 		} else {