The invention provides a laser-induced thermite welding method. The laser-induced thermite welding method comprises the following steps: (1), paving one layer of thermite welding flux on a lower welding block; (2), forming an included angle space between an upper welding block and the lower welding block; (3), obliquely shooting a laser beam from the included angle space, focusing at one end of the thermite welding flux, melting the thermite welding flux, also enabling the surfaces of the upper welding block and the lower welding block to melt for thin layers, forming a thermite welding flux bath and waiting that thermite reaction is fully carried out; (4), closing laser, with the press operation of the second end of the upper welding block, paving liquid welding flux promoting thermite reaction on the whole welding surface between the upper welding block and the lower welding block, extruding welding slags out of a welding seam, and enabling the upper welding block to be fully bonded with the lower welding block; and (5), after solidification, forming a welding joint. Through precise operation in a laser-induced thermite welding process, thermite reaction is sequentially carried out in a controlled manner, the liquid welding flux is uniformly paved, the overflow of air bubbles in the bath is facilitated, the welding slags are extruded out of the welding seam, and air bubble and inclusion defects easily occurring in a traditional thermite welding method are overcome.