As a nationally standard fault diagnosis method,the fault tree analysis is easy to implement and has found wide applications,especially in fault diagnosis of large-scale and complicated electronic devices.The basic concepts and mathematical foundations of fault tree analysis are introduced in this paper.The qualitative analysis and quantitative analysis processes,as well as the determination of the minimal cut set significance are elaborated.Then a CINRAD fault is taken as an example to describe the calculation process of fault tree analysis in detail.Through the significance sorting in descending order,the contribution of end event to the occurrence of top event is determined,which is sorted for fault diagnosis.