Abstract: With the development of the water resource informatization，how to achieve the application integration of the increased heterogeneous systems is a new topic.Web service composition techniques based on MDA（Model Driven Architecture） can complete the application integration of the water resource area better.In this paper，according to the MDA method，the familiar patterns of the Web service composition based on Petri nets are given，and the methods that verify the correctness of the service composition are discussed.Then，the Petri net model is mapped into the executable BPEL4WS.The effect of Web service composition techniques in the application integration of the water resource area is showed through a case.Finally，a conclusion is drawn，and the future work is pointed out.