Abstract: Objective: To better adapt engineering design proposals of metro vehicle depots to the widely adopted BMO (balanced maintenance operation mode), the impact of vehicle BMO on the design of metro vehicle depots is analyzed. Method: For metro vehicle under BMO, the maintenance schedule, workflow, and duration associated with this mode are examined, and recommendations for BMO duration and operation time during engineering design are proposed. Calculation methods for determining the scale of design and the number of maintenance vehicles are presented, and research is conducted on the configuration schemes of related lines and facilities. By analyzing the maintenance cycles, tasks, durations and workflows of the system maintenance mode and BMO, the design scale and the calculated number of maintenance vehicles between the two modes, as well as the required lines and facilities are compared. The impact brought about by BMO is summarized. Result & Conclusion: There is a significant difference between the vehicle maintenance duration regulated by the vehicle BMO and the Code for Design of Metro, affecting the design scale, allocation of vehicles, and requirements for line facilities in vehicle depots. After adopting BMO, the required amount of light maintenance platforms can be reduced by 18%, and the number of maintenance vehicles can be reduced by 57%. It is evident that metro vehicle depot engineering should be designed according to BMO. Under BMO, scheduled maintenance lines should be removed, static adjustment lines can be canceled for depots not undertaking vehicle overhaul tasks, and test tracks should not be added to parking lots due to BMO. The current Code for Design of Metro is not suitable for BMO, and it is recommended to revise the relevant provisions accordingly.