There are many problems in the off-line manual press mounting of tapered roller bearing outer ring of some automobile gearbox shell, which are unstable quality, poor precision, the low efficiency and high labor intensity. In order to solve these problems, we designed a vertical pile press machine. PLC is used to achieve automatic control production, and the stable mounting force provided by air pressure system can adapt to the press mounting requirements of the bearings of eight and nine shift gearbox shell. On being applied to the automatic production line, it can press-mount simultaneously the outer ring of intermediate shaft bearing and the second shaft bearing, and switch rapidly between the eight shift gearbox and the nine shift gearbox. Therefore the automatic production is achieved , which improvs the production efficiency , ensures the assembly quality, and brings higher profit to the enterprise.