A heat-dissipating Zener diode includes a heavily-doped semiconductor substrate having a first conductivity type, a first epitaxial layer having the first conductivity type, a first heavily-doped area having a second conductivity type, a second epitaxial layer, and a second heavily-doped area having the second conductivity type or the first conductivity type. The first epitaxial layer is formed on the heavily-doped semiconductor substrate. The first heavily-doped area is formed in the first epitaxial layer and spaced from the heavily-doped semiconductor substrate. The second epitaxial layer is formed on the first epitaxial layer and penetrated with a first doped area, and the first doped area has the second conductivity type and contacts the first heavily-doped area. The second heavily-doped area is formed in the first doped area.