A high-voltage semiconductor device structure is provided, which includes a drain structure having two curved structures that are insulatedly adjacent to each other and alternatively arranged, and a source structure, a drain extension structure, and a gate structure formed between the two curved structures. By using the curved structures with alternatively arranged configuration, an electrode terminal with a small curvature radius is prevented from being produced, and the electric field accumulation effect is partially eliminated, thereby increasing the breakdown voltage. Meanwhile, the curved structure with alternatively arranged configuration not only reduces the ON resistance, but also utilizes the space effectively, thus, the integration of the semiconductor device on the chip is enhanced, so that the miniaturization requirement of an electronic device is satisfied.