A power semiconductor device having adjustable output capacitance includes a semiconductor substrate having a first device region and a second device region defined thereon, at lest one power transistor device disposed in the first device region, a heavily doped region disposed in the semiconductor substrate of the second device region, a capacitor dielectric layer disposed on the heavily doped region, a source metal layer disposed on a top surface of the semiconductor substrate and electrically connected to the power transistor device, and a drain metal layer disposed on a bottom surface of the semiconductor substrate. The source metal layer in the second device, the capacitor dielectric layer and the heavily doped region form a snubber capacitor.