A metal oxide varistor with heat protection has a body, an insulated washer, a first lead, a second lead and a thermal fuse. The body has two sides and two contacts respectively on the sides. The insulated washer is attached to one contact and has a through hole. The first lead is mounted on the other contact. The second lead is mounted on the insulated washer. The thermal fuse is mounted on the insulated washer and electrically connects to the second lead and the second contact. When the body overloads and overheats, the thermal fuse causes the circuit to open quickly, and the insulated washer keeps the thermal fuse from electrically connecting to the second contact again.