The invention designs an automatic temperature control circuit which has exact control, reliable and stable performance and complete protective measures, and is used for executing effective real time control on the temperature of a tube core of a pump laser in ASE broadband light source. The control device adopts the design proposal of a temperature control system based on Proportion Integration Differentiation (PID) control and pulse-width modulation (PWM) braking mechanism and realizes the designs by adopting a pure hardware circuit; the control device comprises a reference voltage circuit, a pumping tube core temperature testing circuit, a thermoelectric voltage amplifier circuit, a PID controller, a pumping refrigeration current limiting protective threshold set circuit, an efficient PWM control driver, a pumping semiconductor refrigerator and a pumping tube core temperature out-of-limit close protective circuit. The whole circuit has simple and compact design, high reliability as well as heating and refrigerating efficiency, and little self heating, thereby greatly reducing the power consumption and volume of a pumping temperature controller; as the control device has the complete protective function, when the temperature of the pumping tube core exceeds the set range of operating temperature, the circuit sends out the gang control signal to automatically close a drive circuit of the pumping. The pumping refrigeration current limiting protective circuit limits the refrigeration current within the range of the preset maximum refrigeration current range to prevent the pumping from being damaged.