The invention discloses an adjusting method and system for the temperature of a constant temperature apparatus. The adjusting method includes the following steps: adjusting the temperature of a constant temperature apparatus to be a limit junction temperature; when the temperature of the constant temperature apparatus is stable at the limit junction temperature, applying a monopulse square wave voltage with the amplitude 0.8 times of a voltage-withstand value of a to-be-tested device between an anode and a cathode of the to-be-tested device, so that the to-be-tested device generates an expected leakage current and the junction temperature of the to-be-tested device will not rise; adjusting the temperature of the constant temperature apparatus to be a preset case temperature; when the temperature of the constant temperature apparatus is stable at the preset case temperature, applying a reverse bias voltage which is 0.8 times of the voltage-withstand value of the to-be-tested device between the anode and the cathode of the to-be-tested device; and adjusting the temperature of the constant temperature apparatus on the basis of a difference value between an actual leakage current and the expected leakage current of the to-be-tested device, so that the actual leakage current of the to-be-tested device reaches the expected leakage current. Through the adjusting method and system of the invention, the junction temperature of the to-be-tested device that carries out a high temperature anti-bias experiment can reach the limit junction temperature quickly and accurately.