The processing mechanism and application field of high speed milling were analyzed. The high speed milling module of MasterCAM X6 software was studied further. Taking a typical cavity mould part as example, its highspeed milling excavated rough machining parameters and high speed milling contour shape finishing parameters were set. For high speed milling tool path, entities simulation process was done and high speed milling was completed with UCP600 machine tools. Through examination, the part is qualified, the set high speed milling parameters are reasonable.