An over-current protection device comprises a PTC device, first and second electrodes, a first welding metal plate and a second welding metal plate. The PTC device comprises a first conductive layer, at second conductive layer and a PTC polymeric material layer laminated therebetween. The first electrode electrically connects to the first conductive layer. The second electrode electrically connects to the second conductive layer and is separated from the first electrode. The first welding metal plate is formed on an upper surface of the device and connects to the first electrode. The second welding metal plate is formed on the upper surface or a lower surface of the device and connects to the second electrode. The first and second welding metal plates are placed at two opposite ends of the strip-like structure, and each of them has a thickness sufficient to withstand spot-welding without significant resultant damage to the PTC device.