GUI test suite reduction is an effective approach to reduce test cost. Due to the mechanics of message loop and the event- driven characteristic of GUI software, it is difficult to directly apply traditional test suite reduction techniques, such as control-flow based technique and data-flow based technique, to GUI test suite reduction. How to eliminate more redundant test cases without loss of the ability of finding errors is still a great challenge. Combining control flow technique and data flow technique, this paper proposes three test reduction techniques based on source code structure of event handler functions and the data dependencies among them. Experimental results show that two of the techniques that based on the data dependency among event handler functions achieve good results.