The present invention provides a LDNMOS device for an ESD protection structure, by means of disposing a metal portion above the isolation portion and overlapping thereof, so as to protect the internal device from ESD more completely, comprising: a substrate; an ILD; a deep N-well region; a P-body region; a doped region, the doped region defines a diffusion area on the top thereof; a Poly gate electrode; an isolation structure disposed between the Poly gate electrode and the doped region; a contact portion connecting to the diffusion area of the doped region; and a metal portion disposed above the doped region, connecting to the contact portion. Wherein there is an overlap between the isolation structure and the metal portion, the direction of the overlap is parallel to the direction of channel length.