In order to enhance the entire reliability of high-speed punch, the purchased parts were considered as a whole. The influence of purchased parts on high-speed punch was analyzed. Sectional model involving two Weibull distributions of purchased parts in high-speed punch was established. The calculation and test on inflection point were implemented. The FMEA of the early failure period and the random failure period were compared. And the key control technology on purchased parts of high-speed punch was proposed which is significant in reliability analysis and control of purchased parts in other high-speed punching machines.