The invention discloses a hydrogel 3D printing internal environment control device and method. The device comprises a thermal insulation glass shell which is bonded to a connecting base plate at the bottom of the thermal insulation glass shell, then the connecting base plate is mounted by being matched with a liquid trough base plate of a printer, the top of the thermal insulation glass shell is connected to a lifting system cantilever guide rod of the hydrogel 3D printer in a sealing and sleeving mode through a seal rubber cover, and a temperature and humidity sensor is mounted on the rear wall of the inside of the thermal insulation glass shell; an upper ventilation hole and a lower ventilation hole are formed in the right side wall of the thermal insulation glass shell; the upper ventilation hole is sequentially connected with an air sucking pump, an ultrasonic wave humidification generator and a thermoelectric semiconductor square copper tube through a copper tube wrapped with thermal insulation cotton and then is connected with the lower ventilation hole of the thermal insulation glass shell, and an enclosed circulation system is formed. According to the control device, simple mounting parts for being connected with the lifting system cantilever guide rod of the printer and the printing liquid trough base plate are designed, the control device is easily applied to hydrogel 3D printing equipment, the control device is simple in whole structure, small in occupied space, easy to perform control and also easy to realize and popularize, and stable and efficient control over the internal environment is achieved.