The invention discloses a temperature regulating system of a vehicle-mounted system. The temperature regulating system comprises a vehicle-mounted air conditioner, an in-vehicle cooling branch circuit, a battery cooling branch circuit, a semiconductor heat exchange module, a battery heat management module and a controller, wherein the vehicle-mounted air conditioner is used for providing refrigeration power for the in-vehicle cooling branch circuit and the battery cooling branch circuit; the battery cooling branch circuit is connected with the vehicle-mounted air conditioner; the semiconductorheat exchange module is used for providing refrigeration power for the in-vehicle cooling branch circuit and the battery cooling branch circuit; the battery heat management module is connected between the battery cooling branch circuit and the battery; the controller is used for obtaining the temperature regulation required power and the temperature regulation actual power of the battery and regulating the power of the semiconductor heat exchange module and/or a compressor according to the temperature regulation required power and the temperature regulation actual power of the battery. Therefore, when the temperature of the vehicle-mounted battery is too high or too low, the temperature can be regulated, the temperature of the vehicle-mounted battery remains in a preset range, and the condition that the performance of the vehicle-mounted battery is influenced due to abnormal temperature is avoided.