Abstract: The statistical analysis of the inner hole size of CRH380A（L） and CRH380A series MTU rear baffle rings，new/old axle box bearings，new/old axle dust-proof seat size，axle scrap ratio and scrap reason is performed. Through probability analysis of data，the reduction of axle dust-proof seat size of axle box bearings after each retraction is obtained. At the same time，the existing maintenance standards，axle box bearing rear baffle ring and scrap reason are also given. The size tolerance of the optimized dust-proof plate seat is obtained by analyzing the interference of the dust-proof plate seat；the annual cost savings after the optimization standard are calculated based on the analysis of the scrap ratio of axles and the causes of scrap；and the necessity of the optimization of the standard is verified by service life and cost analysis.