Humidity in the air is as ubiquitous as temperature. In the south of Hoang Mai, the weather is warm and humid, and people feel hot and uncomfortable. At the same time, the damage caused by moisture and mold to metal oxidation can happen at any time unknowingly. Optical lenses, magnetic recording materials (including optical discs) , photographic film, Electronic Information Media, electronic components, instruments, instrumentation, powder materials, paper, wood, silk, leather tobacco, food, tea, pharmaceuticals, grain and so on are all the things that need to control the humidity. Among them, the state has clear provisions on the humidity of the drug production workshop: For example, according to the requirements of the state, the pharmaceutical factory must pass the "drug production Quality Management Code" (GMP) certification. Article 17 the temperature and relative humidity of the clean area shall be in conformity with the requirements of the pharmaceutical production process. No special requirements, the temperature should be controlled in 18 ~ 26 °C, relative humidity control in 45 ~ 65% . In order to meet this requirement, air conditioning and purification devices must be installed in the workshop of Pharmaceutical Factory. The control of temperature and humidity is realized by heating, Cooling and adding/dehumidifying devices. To meet the requirements of GMP. Drugs shall be stored in special storerooms and classified according to the prescribed storage requirements. The medicine in storage is stored in the corresponding storehouse according to the requirement of temperature and humidity. In the inspection and EVALUATION STANDARD OF PHARMACEUTICAL MANUFACTURERS: 25.7 is the temperature and humidity of the production workshop controlled by the in vitro diagnostic reagent product without air purification requirement in the production environment. One of the production rules: Air Drying requirements of the operation room should be equipped with air drying equipment, to ensure that materials will not be affected by moisture deterioration. Maintain dehumidification equipment regularly and monitor indoor air humidity. Thus, the pharmaceutical industry needs strict control of temperature and humidity, and dehumidifier is an ideal device to control humidity.