Reflective cup is one of the key components of electrohydraulic shock wave lithotripter.At present,manual polishing is mainly relied on at home.In order to achieve dimensional accuracy,surface roughness,stable quality,high efficiency of the reflection cup,polishing processing parameters of reflective cup was researched based on bonnet tool on the transformed CNC lathe.Based on the analysis of the Preston removal function combining the theory of elliptic Hertzian contact,the important parameters affecting the material removal on the inner surface of the reflective cup were determined.In order to ensure the quality requirements of polishing,the polishing trajectory was optimized.The experimental results show that the requirements on dimensional accuracy and surface roughness of the reflection cup are reached.