The present disclosure provides a method for forming a Lateral Double-Diffused MOSFET (LDMOS). The method includes providing a semiconductor substrate having a first conductivity type; forming a first shallow trench isolation (STI) structure in the semiconductor substrate; and applying a first ion implantation to form a drift region of a second conductivity type into the semiconductor substrate with the drift region surrounding the first STI structure. The method also includes applying a counter-doping implantation to form a counter-doped region having the first conductivity in the drift region and forming a body region on one side of the drift region in the semiconductor substrate. The method further includes forming a gate structure on the semiconductor substrate, wherein one end of the gate structure extends to an area on the body region another end of the gate structure extends to an area on the first STI region.