Certain perpendicularity requirements exist for the mounting face of the speed-shifting pump on the transmission and the drive shaft of the pump. If specified value is exceeded, slant friction between the end face of the larger gear in the pump and the end cover will result, causing pump failure. Loader ZL50 is taken as example to describe the determination method and control measure of the perpendicularity tolerance for drive shaft assembly of the speed-shifting pump. Certain perpendicularity requirements exist for the mounting face of the speed-shifting pump on the transmission and the drive shaft of the pump. If specified value is exceeded, slant friction between the end face of the larger gear in the pump and the end cover will result , causing pump failure. Loader ZL50 is taken as example to describe the determination method and control measure of the perpendicularity tolerance for drive shaft assembly of the speed-shifting pump.