Drying boxes are divided into electric blast drying boxes and vacuum drying boxes according to the different dry substances, and have been widely used in chemical industry, electronic communications, plastics, cables, electroplating, hardware, automotive, optoelectronics, rubber products, molds, spraying, printing, medical, aerospace and colleges and universities and other industries. The huge market demand makes the variety of drying boxes diversified, the structural quality of products is not the same, in order to make people more clearly understand the drying box, with a pair of discerning eyes to identify the quality of drying boxes.