A process method for machining large allowance removal of rotating parts by wire electrical discharge machining was proposed based on the contour approximation method.It included the roughing polygon forming stage,the semi-finishing edge removal stage and the electric discharge grinding stage in the finishing process.The number of polygonal sides was determined,the residual value was defined and the corresponding relationship between the residual value and the number of sides was obtained.The calculation and experimental results show that after the number of sides is more than 32,the change rate of the residual value begins to decrease; the residual value less than 0.5 mm is conducive to the processing of rotating parts.After the number of sides was determined,in order to reduce the processing time,two processing methods of the constant angle method and the multiple method were proposed for contour approximation,and a relatively efficient forming method was obtained through the calculation and comparison of the processing area.The results show that under the condition of the same workpiece diameter,the processing area of the multiple method is smaller than that the method of constant angle,and the processing time reduces by about 34%.The improved process method was verified by machining a titanium alloy workpiece on the middle wire machine tool.After the machining was completed,the radial runout of the rotating part is within ±10 μm measured by the laser displacement sensor.