The invention provides a circuit board welding jig comprising a positioning device, a welding wire penetrating device and a first heating device. The positioning device is used for positioning a first circuit board and a second circuit board so as to be aligned to a first through hole in the first circuit board and a second through hole in the second circuit board. The welding wire penetrating device is used for enabling a welding wire to penetrate through the first through hole in the first circuit board and the second through hole in the second circuit board. The first heating device is used for welding the welding wire to the first circuit board and the second circuit board. By means of the circuit board welding jig, the circuit boards can be welded reliably and efficiently.