The invention provides a testing device of an automatic adjusting arm of a vehicle clearance in high and low temperature environment, belongs to the mechanical technical field, and solves the problem that the performance of the automatic adjusting arm of brake clearance can not be tested in the severe environment of high and low temperature in the prior art. The testing device of the invention comprises a test platform, a control system and a pressure vessel. A test box is arranged on the test platform. An installation bracket is arranged in the test box and used for installing the automatic adjusting arm of the brake clearance; a brake mechanism and a drive mechanism arranged on the test platform and used for being connected with the automatic adjusting arm of the brake clearance; a heating system and a refrigeration system which are connected with the control system are arranged on the part of the test box and used for controlling the temperature inside the test box; and the pressure vessel is connected with the control system. The test device can improve the precision and the stability of temperature control, and realize intellectualized control.