The invention relates to a waterproof structure for prefabricated outer hanging sandwiched wall plates. Each of a transverse spliced joint and a longitudinal spliced joint of the adjacent prefabricated outer hanging sandwiched wall plates is sequentially provided with a metal embedded strip, a first weather resistance glue layer, a first foaming blockage layer, a water guiding layer, a second foaming blockage layer and a second weather resistance glue layer from exterior to interior. A water stop rabbet with the lower exterior and the high interior is further arranged between the water guidinglayer and the second foaming blockage layer of the transverse spliced joint. The section of each metal embedded strip is in an omega shape, and the metal embedded strips are arranged on the outermostsides of the transverse spliced joint and the longitudinal spliced joint. Through a plurality of waterproof facilities, the waterproof performance at the joint positions of the prefabricated sandwiched wall plates is improved; improvement is conducted on the structures of prefabricated sandwiched concrete outer wall hanging plates, through prefabricating forming of clamping grooves for clamping the first foaming blockage layers and the second foaming blockage layers, the safety performance and the waterproof performance are improved; and the structure and installation design of the metal embedded strips are ingenious, and the waterproof performance and the decoration function are combined.