绝大多数通信协议是以ＥＦＳＭ（扩展的有限状态机）来描述的。本文首先给出ＥＦＳＭ的形式化定义，然后提出ＥＦＳＭ的一种等价转换算法及其证明。通过协议转换，可以使生成一致性测试集的方法得到简化，并且生成的测试实例具备一定的诊断数据流错误的能力 The vast majority of communication protocols are described by EFSM (Extended Finite State Machine). This paper first gives the formal definition of EFSM, and then proposes an equivalent conversion algorithm of EFSM and its proof. Through the protocol conversion, you can make the method of generating a consistent test set is simplified, and the generated test instance has a certain ability to diagnose data flow errors