The invention discloses a printed circuit board. One layer of the printed circuit board is provided with copper foil, a plug-in hole and a heat radiation preventing groove, wherein the copper foil is paved on the surface of the layer; the plug-in hole passes through the whole printed circuit board; the heat radiation preventing groove is arranged in the surface of the layer and is not covered by the copper foil; and the heat radiation preventing groove is surrounded at the circumference of the plug-in hole and comprises a first opening facing to a power supply device on the printed circuit board and a second opening not communicated with the first opening. The printed circuit board has a better effect for preventing cold welding.