The grain dryer has strong adaptability to grain varieties and climate environment, and can be used to dry various grains and oilseed crops such as corn, rice, soybean, wheat, sorghum, rapeseed, etc. The grain dryer uses clean hot air as the heat medium, that is, hot air drying. The heat source is a hot air stove that uses coal, oil, natural gas, straw, rice husk, etc. as the fuel, or steam as the heat source.