Abstract: The most wheel-set assembly of rail transit vehicle adopts cold pressing technology. But due to the particularity of low-floor vehicle gearbox structure，it is necessary to assemble the press through the CNC wheel set press to meet the technical requirements of the low-floor wheel-set. In this paper，the wheel set assembly process of low-floor rail vehicles is analyzed. Combined with the structure of the wheel set and the interface of the CNC wheel set press，the new process is developed and researched. A set of low-floor wheel-set press fixture is designed and manufactured to meet the requirements for the wheel-set press of low floor rail vehicles.