The invention discloses a rack-mounted environment 
humidity control device, and relates to the technical field of modular 
data center environment control, the rack-mounted environment 
humidity control device comprises a device body, an 
airflow circulation unit, a dehumidification unit, a humidification unit and a central 
control unit, the 
airflow circulation unit comprises an air inlet, an 
airflow circulation channel and an airflow circulation fan, an air inlet is formed in the front part of the device body, an airflow outlet is formed in the rear part of the device body, and two airflow circulating fans are mounted on the device body; according to the rack type environment 
humidity control device, by arranging the airflow circulation unit, the dehumidification unit, the humidification unit and the central 
control unit, three different working 
modes can be achieved, so that the cost can be saved, meanwhile, the space occupied by the device is saved, the humidification function and the dehumidification function are combined into one, and the environment humidity control device is convenient to use. Therefore, the device can realize the humidifying and dehumidifying functions.