For the deficiency of traditional failure mode and effects analysis ( FMEA) in solving risk ranking problem for related failure modes, this paper proposed a risk assessment method based on ordered weighted geometric averaging (OWGA) operator and fuzzy decision making trial and evaluation method (DEMATEL). Firstly, fuzzy evaluation of failure modes was carried out which is aggregated by OWGA operator, and the aggregated value was taken as the influence degree of failure cause effect on corresponding failure mode. Then, the initial direct influence matrix was constructed by DEMATEL method, normalize this matrix to compute the total influence matrix. According to the total influence matrix, the relation degree of each failure cause was calculated, based on which the failure risk assessment of the system can be carried out . The proposed method was applied in FMEA risk analysis of basic parts of metro car door system, the feasibility and effectiveness of the proposed method is verified by comparing with the results of the RPN method.