The investment scale of urban rail transit industry is large，the operation cost is high，and cost control becomes an important management issue of the subway company. Maintenance costs as one of the main operating costs of the subway project，depending on the type of equipment，operating environment，asset life cycle，maintenance capabilities and maintenance of a variety of factors such as the impact of different operating periods，maintenance costs between different lines tend to exist Differences，the cost of hard to find. Based on the analysis and research of the consumption quota of Xi’an metro car and AFC，this paper puts forward that maintenance quota management is an effective way to explore the cost law，adapt to the needs of the development of the line network，control the operation cost continuously and improve the operating benefit.