An auto-precision feeding system was designed for pig breeding. According to system components both hardware and software, its mainly components of hardware and software and their function were described in detail. The mainly hardware of precision feeding field system were PLC, stepping motor, driver and discharger. Software application program was developed by using KingView, which was composed of precision feeding interface and feed adding interface. Based on hardware and corresponding software application, automation and precision feeding system was achieved in the whole. The results of running indicated that the system runed stable and reliable, it realized automation and precision feeding , and its maximum error would be less than ±2% within certain range.