An over-current protection device includes a first metal layer, a second metal layer and a heat-sensitive layer laminated therebetween. The heat-sensitive layer exhibits a positive temperature coefficient (PTC) characteristic and includes a first polymer and a conductive filler. The first polymer consists of polyvinylidene difluoride (PVDF), and PVDF exists in different phases such as -PVDF, -PVDF and -PVDF. The total amount of -PVDF, -PVDF and -PVDF is calculated as 100%, and the amount of -PVDF accounts for 48% to 55%. The conductive filler has a metal-ceramic compound.