An electrostatic discharge protection device, having a P-type semiconductor substrate set as floating; a first N-well and a second N-well formed in the P-type substrate; a first P-doped region and a second P-doped region formed in the first N-well and the second N-well, respectively. The first N-well and the first P-doped region form a first diode, and the second N-well and the second P-doped region form a second diode. A first N-doped region and a second N-doped region formed in the first N-well and the second N-well respectively. A third P-doped region is formed in the P-type substrate, wherein the third P-doped region is disposed between the first N-well and the second N-well, and the third P-doped region is electrically connected to the first N-doped region and the second P-doped region.