In view of the problems of poor pellet preheating and drying effect and serious air leakage at the feed port in the blast drying section，the pellet grate system is simulated and analyzed by CFD software，and the calculation results show that the poor pellet preheating and drying effect is caused by serious air cross-winding in each process section. The serious air leakage at the feed port in the blast drying section is caused by the insufficient smoke exhaust capacity of the grate chimney. When the reheating air volume of the grate is 2 500 ~ 2 750 m³ /min( when each process section is not crosswinded) ，the grate has the best effect on the preheating and drying of the pellets. Closing the valves of a pair of bellows on the lower side of the preheating I section can effectively strengthen the effect of preheating and drying pellets in the draining section. The blast drying section is introduced into the main pumping process，which can solve the problem of serious air leakage at the feed port，and a valve is added in the pipeline to adjust the pressure of the drum dry section. Simulation shows that when the valve opening is between 55% and 60% ，the pressure in the drum dry section is maintained at a slightly negative pressure.