Abstract: The scientific formulation of maintenance cycle of door system has important significance to guarantee the urban rail vehicle running safely and efficiently. In this paper, the fuzzy multi-object optimization method was applied to optimize the maintenance cycle of urban rail vehicle door system. Firstly, determined the relationship among availability, economy, task reliability and maintenance cycle. Then, took the cost and economy as the optimization objective and the task reliability as the constraint conditions, established a fuzzy multi objective optimization model based on Fuzzy Analytic Hierarchy Process (AHP). Finally, applied the proposed model to the door system of a metro line 2, verified the validity of the model.