Abstract: With the upgrading of crawler tractor，power has become a trend，the transmission gearbox shell model and the rear axle housing of the long slide structure hole，the intermediate shaft with deep design，present situation of many varieties of small batch has made by special equipment tool processing is not reality.In the premise of a machining center using the existing equipment，through the crawler tractor gearbox shell deep-hole machining examples contrast，the process design of shell deep hole processing was introduced，especially in the inner hole machining process.