Abstract: in view of the automobile engine connecting rob bolt hole, hole size head existing processing technology in production efficiency, the qualified rate is low and the problem of machining accuracy is not enough. Based on the analysis of the principle in process, put forward a clamping the workpiece, trasfer, multitool crude refined composite processing of new process. According to the process content characteristics determine the horizontal machining posture of the connecting rod cap outwards. Then determine the set up in bed in the middle of round, nc rotary table on the set of 5 location, Each location clamping 3 pair of workpiece, location 2&4 to complete the bolt hole processing, 3&5 complete size head hole processing. Complete overall layout scheme of loading station 1. According to the overall plan detailed design the special fixture and special structure of simple box. Practical production shows that: Special equipment for the production program is controlled in 1 million, at more than 99.9% pass rate. The precision meet or exceed the technical requirements.