In recent years,urban rail transit (URT) systems have rapidly developed in China,however,their existing strategies for vehicle maintenance are still based on experiential and qualitative methods which result in either high cost or emergencies.In this paper,a tentative attempt at introducing the fuzzy set theory into quantitative analysis and assessment of URT trains’ failures was presented.Based on the proposed FMEA-fuzzy model,a computer aided system for URT maintenance optimization was developed.The overall structure and procedure of the system were described in detail,and the important issues,including the development environment,improvement to FMEA table,acquisition of weight distribution matrix P,and setting of fuzzy vector R,were also discussed.Initial application into the vehicle maintenance of Shanghai Metro System shows,that the proposed model and computer aided system have a good performance and consequently are worth further development. In recent years, urban rail transit (URT) systems have rapidly developed in China, however, their existing strategies for vehicle maintenance are still based on experiential and qualitative methods which result in either high cost or emergencies. 这 this paper, a tentative attempt at introducing the fuzzy set theory into quantitative analysis and assessment of URT trains’ failures was presented. Based on the proposed FMEA-fuzzy model, a computer aided system for URT maintenance optimization was developed. The overall structure and procedure of the system were described in detail. , and the important issues, including the development environment, improvement to FMEA table, acquisition of weight distribution matrix P, and setting of fuzzy vector R, were also discussed.Initial application into the vehicle maintenance of Shanghai Metro System shows, that the proposed model and computer aided system have a good performance and made are worth more development.