The structure of the system becomes more and more complex, and the problems of systematicness and reliability become more and more serious. The more complex a system is, the more information it can hold, the more important it is, the more powerful it is, and the wider its scope of application, it could even be catastrophic. Therefore, the overall reliability index of the system is evaluated and analyzed quickly, effectively and accurately, and the overall actual safety performance of the system is estimated correctly and reasonably, it is of great practical significance to reduce the security risk of enterprise system..