The invention relates to an over-current protector, which comprises: a substrate with chemical crosslink positive-temperature factor (PTC) and two electrode foils, wherein its production comprises: a, providing the macromolecule mixture with PTC character, which has the first polymer with function group X, the second polymer with the function group Y, and the conductive powder, heating it into the polymer softening point to mixed melt, to obtain the character of crystal thermal plastic; b, compressing the macromolecule mixture into sheet macromolecule substrate; c, stacking the sheet macromolecule substrates into one-layer stacked polymer layer; d, connecting two electrode foils into the upper and lower surfaces of said polymer layer; e, thermally compressing the upper and lower electrode foils and the stacked polymer layer, to generate the original chemical crosslink reaction of function group X and function group Y, to form one chemical crosslink PTC substrate. The inventive substrate can resist the high voltage at 600V. |