In order to optimize software structure and increase software reliability in software early development, based on invalidation mode, propose a software architecture reliability analysis approach, which called SABRA. Combine mature reliability engineering techniques with software invalidation mode analysis technology, analyze correlation among failure modes. According to sensitive element and unreliable element in feature recognition frame of failure mode, carry out fault tolerance and failure avoidance design for corresponding unreliable part, and find out system weak points by establishing event tree. The results show the method is easy and effective to improve system reliability.