Abstract:This paper discusses Fault Tree Analysis(FTA) technology, uses FTA to analyze a variety of software elements causing software system failure, and constructs software system fault tree through determining all software failure combination of reasons. Then generates the minimum cut sets of fault tree，analyses the security constraint conditions of cut sets，and analyzes the testing data according to the security constraint conditions. Thereafter, the testing case algorithm is generated．Practice shows the fault tree analysis technique can be used to guide the design of software testing, reflecting the systematic, accuracy and predictability of systems engineering methods to study software testing.