The testing cases or fault of User Datagram Protocol(UDP) communication are difficult to be injected into the testing environment when testing some control and communication software. This paper presents a new approach of building UDP communication simulation testing software using Unified Modeling Language(UML),and introduces the implementation technique of multiple UDP communication software interacting with the software under test. With this simulation testing platform,users can easily input the testing case or fault into the simulation testing environment,moreover,the efficiency and effectiveness of testing are improved.