The invention discloses an active heating-type overheating protective device which is composed of a heating sheet 2, a pin 1 and a bimetallic strip 7. The bimetallic strip 7 is tightly attached to the heating sheet 2. The pin 1, a heating resistor 3 in the heating sheet 2 and the bimetallic strip 7 are serially connected in sequence. In use, the protective device is required to be serially connected with a controlled device, and current through the heating resistor 3 is enabled to be consistent with current of the controlled device. When the current of the controlled device is abnormally increased, and the heating resistor 3 actively emits heat to enable the bimetallic strip 7 to act quickly for disconnecting a circuit, so that the overheating fault of the controlled device is prevented. The bimetallic strip 7 is reset for connecting the circuit when the temperature of the controlled device and the temperature of the heating resistor 3 are lowered, and the controlled device can operate normally again. The protective device provided by the invention fully protects the safety operation of the controlled device, and the service life of the controlled device is prolonged.