Controllable circulating constant temperature system

The utility model relates to the technical field of constant temperature device structures, in particular to a controllable circulating constant temperature system. A plurality of unit intervals are arranged in the box body and are sequentially arranged at intervals in the vertical direction; the air inlet duct is positioned on one side of the air inlet of the unit interval; the air outlet duct is located on one side of an air outlet of the unit interval; the adjusting interval is located below all the unit intervals, the two ends of the adjusting interval communicate with the inlet end of the air inlet duct and the outlet end of the air outlet duct correspondingly, and a first cross-flow fan for sucking air in the air outlet duct into the air inlet duct and an adjusting module for heating or cooling the air in the adjusting interval are arranged in the adjusting interval; the air outlet of each unit interval is provided with a monitoring module for monitoring the air outlet temperature of the unit interval a