Abstract: High-voltage semiconductor devices are provided. The high-voltage semiconductor device includes a substrate having a first conductive type and a gate region disposed on the substrate. The high-voltage semiconductor also includes a source region and a drain region disposed on two sides of the gate region respectively. The high-voltage semiconductor also includes a linear doped region disposed between the gate region and the drain region, wherein the linear doped region has a nonuniform doping depth and the first conductive type. The high-voltage semiconductor further includes a first buried layer disposed under the source region and having the first conductive type.