A semiconductor device for electrostatic discharge protection is disclosed, and at least comprises a high-voltage parasite silicon controlled rectifier (HVSCR) and a diode. The HVSCR has an anode and a cathode, and the cathode of HVSCR is coupled to a ground. The diode, coupled to the HVSCR in series, also has an anode and a cathode. The anode of the diode is coupled to the anode of the HVSCR, and the cathode of the diode is coupled to a terminal applied with a positive voltage. The diode has a second conductivity type zone that could be constructed to form several strips or small blocks spaced apart from each other. Those small blocks could be any shapes and arranged regularly or randomly.