In order to optimize the maintenance process of urban subway trains in China and reduce the stress of maintenance personnel, the work aims to study the working environment and working condition of subway train maintenance personnel in China and put forward the optimization design strategy. The maintenance task and operation process in man-machine-environment system were analyzed, and then the problems were found and the optimization methods were explored. Through field investigation and collection of relevant literature and maintenance process, the maintenance system model of man (train maintenance personnel) - machine (train to be inspected, tools/equipment) - environment (maintenance environment and its impact) was deduced and constructed, so as to explore and find the stress source of maintenance personnel stress during maintenance tasks. Combined with psychological theories of coping with stress, three strategies for managing stress were summarized, including remould stressors, stress response optimization, support or assistance. From the perspective of maintenance personnel, it was suggested that design optimization of train maintenance tasks could be implemented in three ways such as human-machine adaptation, interactive logic and Cognitive aid. The work quality of train maintenance personnel can be effectively improved by conducting systematic analysis to explore the sources of stress for maintenance personnel under the existing train maintenance system and utilizing stress response strategies and optimization approaches.