LDMOS device including a drift region, a body region, a gate dielectric layer, a polysilicon gate, a source region, a drain region and a common dielectric layer, the common dielectric layer covers a portion, between a second side of the polysilicon gate and the drain region, of the surface of the drift region, extends onto the surface of the polysilicon gate and also covers part of the surface of the drain region, a self-aligned metal silicide is formed on portions, not covered by the common dielectric layer, of the surfaces of the polysilicon gate, the source region and the drain region, and the common dielectric layer serves as a growth barrier layer of the self-aligned metal silicide; a drain terminal field plate is formed on a portion of the surface of the common dielectric layer; and a portion of the common dielectric layer serves as a field plate dielectric layer.