After CRH5A EMUs brake discs were repeatedly mounted on wheelsets by pressed-on fitting, the inner hole diameter of the hub would usually be out of the limits of tolerance, so it was difficult for the interference to meet the existing maintenance technical specifications. As a result, a lot of discs which the inner hole diameters of the hub were out of the limits of tolerance were scrapped and the EMUs maintenance cost increases. In order to reduce the maintenance cost of EMUs, the minimum interference of the hub and axle was determined to 0.208 mm by calculation and tests, and calculated value of fitting-on force was 230~345 kN, which satisfied the requirement of new brake disc fitting-on force of 225~400 kN; Eight hubs which the inner hole diameters were out of the limits of tolerance and interference of 0.208 mm were mounted on wheelsets by pressed-on fitting and tested by counter-pressure, and the results showed that the actual measured fitting-on force was greater than 225 kN and conformed to calculated values, and the discs didn’t incure any displacement on the axle in the counter-pressure tests, which indicated that the brake disc pressure was qualified. This showed that the minimum interference 0.208 mm recommended in this article was reasonable and could be used to revise existing maintenance technical specifications.