Based on the previous research of small batch of grain drying process, exchange the batch type recirculating grain dryer tube for heat exchanger with plate heat exchanger, with easier access to 100 DEG C high temperature steam instead of 800 DEG C flue gas, at the same time, plate heat exchanger can also adopt a more efficient material. Finally, using the matlab optimization toolbox for plate heat exchanger model optimization, under the guarantee for thermal efficiency unchanged, the size of the heat exchanger was optimized. Research has shown that after improvement is higher than before the heat exchanger in heat efficiency, and reduces heat exchanger area and the waste materials.