Financial system demands high standard for failure diagnosis, and financial products in this system have a whole set of instruction documents covering design to production and also detailed parameters, which are all clearly defined. Based on a brief introduction of PDM and FMEA, the paper proposed a method of failure tree generated by PDM combining with FMEA to diagnose and maintain financial system. This method can execute diagnosis by the information of formation, function, and maintenance of financial products, integrated with diagnosis information acquired in product design period. It would make the processes of product design, failure diagnosis and product maintenance as an organic whole. The paper illustrated in detail the principles of knowledge and regulation for creating failure tree generated by PDM combining with FMEA, and the method was further testified on ATM case.