The invention discloses a high-stability Zener diode which comprises a silicon substrate, silicon oxide, a P well, a P-type heavily doped region, an N-type heavily doped region, two metal electrodes and a polycrystalline silicon, wherein the silicon oxide is arranged on the upper surface of the silicon substrate; the P well is arranged in the silicon substrate; the P-type heavily doped region andthe N-type heavily doped region are adjacent and are arranged in the P well; the two metal electrodes are arranged on the upper surface of the silicon substrate and are respectively in contact with the P-type heavily doped region and the N-type heavily doped region; and the polycrystalline silicon is arranged on the upper surface of the silicon oxide above the N-type heavily doped region and is connected to zero potential or low potential. The invention also discloses a manufacturing method of the Zener diode. The invention is characterized in that the polycrystalline silicon is deposited on the silicon dioxide above the N-type heavily doped region and is connected to the zero potential, thus the electric field of the surface of the N-type heavily doped region vertically points at the silicon surface so that the surface current is changed into volume current, thereby reducing the influence of various adverse factors at the interface of the silicon and the silicon oxide on the stability of the Zener diode, and effectively improving the stability of the Zener diode.