A varistor is broadly used as an over-voltage protection component and surge absorption component for circuit, equipment and components because of its non-linear volt-ampere character. Irrespective whether the varistor is used in power circuitry or electrical circuitry, if transient over-voltage happens frequently, the varistor will operate frequently to protect electrical equipment and components by suppressing the amplitude of the over-voltage, absorbing and releasing the surge power. However, the frequent operation will inevitably cause the performance degradation of a conventional varistor, even cause the varistor to lose its effectiveness. Therefore, when the conventional varistor suffers transient over-voltage, it will rapidly get partial breakdown therefore potentially cause fire. The conventional varistor with thermal protection has the following disadvantages: firstly, the conventional varistor with thermal protection has a complex structure such as a traditional module-type varistor with thermal trip device or a thermally protected varistor disclosed in Chinese patent number CN02222055.0, published on Feb. 12, 2003; secondly, conventional varistor with thermal protection has slow response rate of over-heat protection; furthermore the conventional varistor does not have the ability to handle and to withstand large amount of current impact and as a result it may easily lose its effective circuit protection. Such as a traditional flake-type varistor with thermal trip device, or a varistor which is connected externally with an organic-type or alloy-type thermal fuse as disclosed in Chinese patent number CN00237913.9, published on Oct. 31, 2001.