The invention discloses an explosive welding method of arranging multiple reinforcing ribs between large-area double-layer steel plates. The explosive welding method comprises the following steps of first-stage explosive welding: respectively fixing a die plate I, a die plate II and the reinforcing ribs on a base plate in a spot welding way, putting gap posts on the die plate I, putting an upper panel on the gap posts, arranging explosive on the upper surface of the upper panel, and carrying out the explosive welding; and second-stage explosive welding: overturning welded object obtained in the first stage, taking away the die plate I and the die plate II, filling a die plate III, covering the die plate I on the die plate III, putting the gap posts on the die plate I, putting a lower panel on the gap posts, arranging explosive on the upper surface of the lower panel, and carrying out the explosive welding. According to the explosive welding method disclosed by the invention, compared with the explosive loading amount adopted in an engineering practice in the past, the explosive loading amount is saved by about 18%; a boundary effect subduction method, which refers to a method of additionally arranging lengthened plates at two ends of a cover plate along a detonation spread direction, is adopted; and the explosive using amount is reduced, the welding rate is up to 100%, the strength of a combination interface exceeds that of base material, and the explosive method has the advantage of manufacturing large-area reinforcing rib double-layer steel structural components in good quality and low price.