An over-current protection device includes two metal foils and a PTC material layer. The PTC material layer is laminated between the two metal foils and has a resistivity less than 0.4 Ω-cm. The PTC material layer includes crystalline polymer and electrically conductive ceramic filler dispersed in the crystalline polymer. The conductive ceramic filler is of HCP structure and includes 70-95% by weight of the PTC material layer. The trip jump value of the over-current protection device after 300 times trip is less than or equal to 25. The resistance repeatability of the device can be effectively improved by adding the conductive ceramic filler.