Abstract: Stochastic Petri nets can be mapped into a time-continuous homogenous Markov chain with state space isomorphic to the reachability graph of SPN.While analyzing the system performance，the state space of stochastic Petri nets increase exponentially with the enlarger of the system scale，which cause the complexity of system modeling.Fuzzy Isomorphic Method（FIM） is presented，in which Fuzzy Mathematics（FM） and SPN are adopted as formal theory bases.Compared with traditional methods，Fuzzy Isomorphic Method can be reduced state space so as to easy isomorphic modeling system.As a example，it gets a closer look at the reliability of communication needed for moving-block operation of Europe Train Control System with Fuzzy Isomorphic Method.

Key words: Stochastic Petri Nets（SPN）, continuous time Markov chain, fuzzy isomorphic, simulation

摘要： 随机Petri网（SPN）可以同构于一个连续时间马尔可夫链，但在进行系统性能分析时，其状态空间随着系统规模的增大而呈指数性增长，造成系统无法同构分析，结合模糊数学理论提出一种模糊同构（FIM）方法，该方法可以约简复杂状态空间以便同构分析，最后应用该方法分析欧洲列车控制系统（ETCS）在移动闭塞区间条件下无线通信的可靠性，以验证该方法的可行性。

关键词: 随机Petri网, 连续时间马尔可夫链, 模糊同构, 仿真