Heat Pump Dryer works based on refrigeration cycle. Refrigerant absorbs heat from ambient environment, and then be processed by the compressor to high-temperature and high-pressure gas. The high temperature and high humidity resistant internal circulating fan transfers heat from the condenser to the drying room, forming a circulating hot air in the drying room to evaporate the moisture in raw material. And the water vapor is discharged by the moisture exhaust system.