Automobile parts have complex shape, the cutting amount in numercial control (NC) machining are traditionally selected based on experience of programmers, which will lead to rational amount of cutting personal dependent, so the machining efficiency is difficult to ensure. In order to systemtically study the influency of processing features in machinery machining of automobiole parts on selection of optimal cutting amount, based on finite element simulation of cutting machining, cutting data system for automobile parts based on processing features was developed. By integrated in UG CAM module, the data system based on UG NC programming was formed. The process features were classified according to the requirements in machinery machining of automobile parts. The laws of influence on cutting temeprature by precessing feature parameters, cutting amount, as well as cutting tool geometry parameters were obtained by using Deform 3D finite element simulation and through multielement regressive analysis. Optimization of cutting amount was obtained based on Makarov cutting temperature conversation law, the process features cutting data system software of automobile parts was developed by VC++ software. The results show that this system softwrae can effectively solve the problems of unreasonable cutting amount selection and low machining efficiency from experienced programmers.