In order to achieve the processing of double eccentric shaft with phase requirement on ordinary lathe, a selfeccentric lathe fixture with the function of straightening phase position was designed and produced. It has the advantages of easy operation, rapid positioning. Not only it can well meet the requirements of processing precision, improve work efficiency, reduce production costs; but also the demand for the workers’ processing skills is not high. Trial samples and field test of the lathe fixture have proved good results in use and that desired goal is achieved. As it has the certain value to popularize,this technology has been applied for the invention patent.