The invention provides a semiconductor device with a voltage-resistant structure and a manufacturing method thereof, relating to the technical field of semiconductor chips, including: an N-type substrate, an N+ region, a P-body region, a voltage-resistant oxide layer, a polysilicon region, and an N+ source region , gate oxide layer, polysilicon gate, dielectric layer isolation, device source metal and device drain metal. Wherein, the voltage-resistant oxide layer is respectively arranged on both sides of the central region of the N+ region, and is attached to the side regions of the N+ region respectively. within the shape area. This technical solution alleviates the technical problem of poor withstand voltage performance of the device structure in the prior art, effectively ensures the withstand voltage performance of the device, improves the saturation current of the semiconductor device, reduces the on-resistance of the device, and effectively utilizes the device area , reduces the production cost of the device, and improves the conduction performance of the semiconductor device.