The invention discloses a selective welding carrier and a welding method thereof. The welding method comprises the following steps: adjusting a state and a welding parameter of a selective welding machine, and placing a welded plate into the selective welding machine; spraying a soldering flux; entering a preheating zone to preheat the bottom of the welded plate; entering a welding zone, and starting a hot air preheating device on the top of the welded plate to perform hot air preheating; meanwhile, preheating tin penetration difficult points; starting welding after preheating is finished; moving a welding spray head among welding spots at a uniform speed, reaching the welding spots in sequence, and performing welding; performing welding quality inspection, and returning to the step 1 to readjust the welding parameter if the welding quality is unqualified; and performing batch production if the welding quality is qualified. Through adoption of the method, 100 percent tin penetration can be reached effectively; a judgment standard is simple and clear; an industrial standard is exceeded; the welding spot reliability is enhanced; and the quality is ensured.