A PTC composition comprises crystalline polymer and conductive ceramic filler dispersed therein. The crystalline polymer has a melting point less than 90 DEG C. and comprises 5%-30% by weight of the PTC composition. The crystalline polymer comprises ethylene, vinyl copolymer or the mixture thereof. The vinyl copolymer comprises at least one of the functional group selected from the group consisting of ester, ether, organic acid, anhydride, imide or amide. The conductive ceramic filler comprises a resistivity less than 500 [mu][Omega]-cm and comprises 70%-95% by weight of the PTC composition. The PTC composition has a resistivity about 0.01-5 [Omega]-cm and its resistance at 85 DEG C. is about 103 to 108 times that at 25 DEG C.