The utility model discloses a drying device which comprises a drying box body and a heat source generator, wherein an air inlet is formed at the front end of the drying box and a heat exchanger is arranged at the air inlet portion. The heat exchanger comprises a guide-in pipe, a guide-out pipe and a plurality of heat exchanging pipes, wherein the heat source generator is connected with an inlet of the guide-in pipe, an outlet of the guide-in pipe is communicated with an inlet of each heat exchanging pipe, an outlet of each heat exchanging pipe is communicated with an inlet of the guide-out pipe, and an air outlet at the rear end of drying box body is connected with an draught fan which guides airflow out of the drying box body. After steam is used for exchanging heat and goods are dried, energy consumption is low, drying temperature is suitable, the drying temperature can not be excessive high particularly when wood pieces are dried due to the fact that equilibrium moisture content is relatively low in the drying process caused by excessive high temperature, gradient of moisture content on a wood transverse section is steep, drying defects such as cracking and shrinking are easily produced, and quality of the wood pieces is influenced.