The invention provides a printed circuit board. A copper foil, an insert hole and an anti-thermal relief groove are arranged on one layer of the printed circuit board, wherein the copper foil is paved on the surface of the layer; the insert hole runs through the whole printed circuit board; and the anti-thermal relief groove is formed on the surface of the layer and not covered by the copper foil, surrounds the insert hole and comprises an opening fading a power supply positioned on the printed circuit board. By the printed circuit board, not only the condition of insert hole cold-welding caused by over-high thermal relief speed can be avoided, but also a resistance value between a pin of an insert and the power supply is relatively lower.