The invention provides a lateral high-voltage device, and the device comprises a dielectric trench. Doped strip overlapping structures of different doping types which are arranged alternately are disposed at at least one of the following positions: a part below the dielectric trench, the left side of the dielectric trench and the right side of the dielectric trench. The device also comprises a dielectric layer, a volume field plate, a polysilicon gate, a grid lower oxidation layer, a first N-type heavy doped region, a second N-type heavy doped region, a P-type heavy doped region, a P well region, a first N-type doping strip, a second N-type doping strip, a third N-type doping strip, a first P-type doping strip, and a second P-type doping strip. The bottom of a conduction circuit is a P-type substrate. According to the invention, the dielectric trench is introduced to a drift region, and the surface area of the device is reduced while the withstand voltage is maintained. Moreover, the specific on-resistance of the device is reduced. The overlapped heavy doped N strips and P strips are introduced to the drift region of the device, thereby providing a low-resistance conduction loop for the on state of the device, further reducing the specific on-resistance of the device, and finally achieving the purposes of effectively reducing the area of the device and the on-resistance.