1.5%。An automatic feeding system was developed based on the pneumatic conveying principle, which took S7-200 PLC as controller and touch panel as human machine interface. System structure, main function and working principle of the feeding system were introduced. The design and realization process of the hard circuit and software were discussed. Velocity with feed empty, feeding time and stopping time were setting by the PLC software to automatic control feeding. Experimental results showed that the feeding system met the design requirements. Feeding volume could be 1.1t/h at 320m. The quantitative accuracy was ±1.5%.