The invention provides a laser welding method for cold-rolled steel plates for a car. The method comprises the following specific steps that 1, two cold-rolled steel plates are taken, oil dirt on thesurfaces is removed, and a welding clamp is prepared for standby application; 2, the two cold-rolled steel plates subjected to dirt removal treatment in the step 1 are placed on a working table in a spliced manner and fixed through the welding clamp, and a gap exists between the two cold-rolled steel plates; 3, the gap between the two cold-rolled steel plates in the step 2 is filled with manganesecopper alloy welding filler; 4, a laser device is selected, and laser device machining parameters are set; and 5, the laser device in the step 4 is adopted for irradiating the spliced portion of thetwo cold-rolled steel plates, the spliced portion is fused, solidified and cooled to form a high-quality weld seam, and welding of the two cold-rolled steel plates is completed. According to the method, the problem existing in the prior art can be solved fully, meanwhile, the mechanical property of the welding joint can be improved, and the alloying degree and the production cost of the weld seamare reduced.