Abstract: At present, the automatic feeding system of sows in pig farm mostly adopts the method of sow feeding stations in developed countries, which realizes automatic feeding, however it is impossible for each sow to eat according to the prescribed time, and it is easy to cause cross infection.This project studies an automatic feeding system which uses computer and programmable logic controller（PLC） for central control, through controlling the operation time of the feeder, the feed is added to the trough in each sow’s single pen in turn, so as to realize the timing quantitative and accurate feeding for each now. The parameters such as the diameter of the feeding pipe, the rotating speed of the screw shaft and the elevation angle of the feeding pipe were determined by orthogonal test and variance analysis.The feeding error is controlled within 4%, the precise automatic feeding is realized, and the normal production and management level of the pig farm are ensured.