The invention discloses a method for welding a steel plate by multi-layer welding. The method comprises priming welding, filling welding and cosmetic welding, wherein the cosmetic welding comprises the steps of respectively performing first pass welding and second pass welding on the surfaces of two steel plates to be welded so as to form a first-pass weld pass and a second-pass weld pass, then performing third pass welding on the first-pass weld pass and the second-pass weld pass to form a third-pass weld pass connecting the first-pass weld pass and the second-pass weld pass. The method for welding the steel plate by multi-layer welding can play the role of slowing down the cooling of the first-pass weld pass and the second-pass weld pass through the third-pass weld pass, and simultaneously, normalizing is carried out on welding points. After being austenitized, the steel plate tissues in a heat affected zone and a fusion zone slowly cool down, so that the welding points form pearlite tissues with fine pearlites, thereby improving the mechanical properties of the welding points such as toughness and the like.