Abstract: A new machining method is put forward by studying the parts of triple eccentric butterfly valve. Based on the analysis of turning and the characteristics of conical parts, by translating and rotating the coordinate system, skillfully using the conic polar coordinate equation and the simultaneous CNC lathe turning relationship, the section equation of the valve plate and the surface equation of the sealing surface are derived, so as to establish a new workpiece processing model. Then, the setting of processing parameters is discussed, and the processing effect is simulated based on MATLAB software. After the actual processing comparison test, this method simplifies the process, The common CNC lathe can also process the eccentric cone workpiece, reducing the programming difficulty, effectively improving the part processing quality and production efficiency, and providing experience and reference for actual production.