The present invention provides a high-voltage semiconductor device including a deep well, a first doped region disposed in the deep well, a high-voltage well, a second doped region disposed in the high-voltage well, a first gate structure disposed on the high-voltage well between the second doped region and the first doped region, a doped channel region disposed in the high-voltage region and in contact with the second doped region and the deep well, and a third doped region disposed in the high-voltage well. The high-voltage well has a first conductive type, and the deep well, the first doped region, the second doped region, the doped channel region, and the third doped region have a second conductive type different from the first conductive type.