Vacuum freeze dryer is referred to as freeze dryer for short. The freezer can be operated intermittently or continuously. According to the system, the freezer is composed of four main parts: refrigeration system, vacuum system, heating system and control system; According to the structure, it is composed of drying box (or freeze-drying box), condenser (or cold trap), refrigerator, vacuum pump and valve, electrical control elements, etc. The vacuum freeze dryer is applicable to the drying of high-grade APIs, Chinese herbal pieces, biology, wild vegetables, dehydrated vegetables, food, fruits, chemicals, pharmaceutical intermediates and other materials The freeze-vacuum drying process is free of impurities, which can keep the original ingredients and active ingredients of materials and the shape of materials from being damaged. Put the materials into the material box for freezing after startup. In the freezing process of materials, on the one hand, the vacuum system vacuums and takes part of the water away. On the other hand, when the material is frozen, the water contained in some molecules is discharged to the surface of the material to freeze. After the freezing requirements are met, the material is heated and dried by the heating system, and the water contained in the material is brought to the freezing trap box by vacuuming to freeze, so as to meet the freeze-drying requirements of the material.