Abstract: The finite state automata was used to model distributed discrete event systems, then we proposed an  algorithm of safe diagnosability for distributed discrete event systems. First, we got the global model of the system, pruning and determining whether the given system could be diagnosed or not. If the system could be diagnosed,  the safediagnostor of the system was constructed. Then the safe labels were added to the global model to determine whether the system was safe diagnosable or not. The experimental results show that the algorithm can judge whether the distributed discrete event system is safe diagnosable or not, and the solution space is reduced. The state numbers are approximately reduced by 7 times in the best case, and the state numbers are approximately reduced by 5.45 times in the average case.

Key words: fault diagnosis, distributed discrete event system, safe, diagnostor