The invention discloses an integrated construction method for overlapping a prefabricated guard post and a structural wall. Space is reserved between the structural wall and the guard post. A leveling layer and a waterproof layer are sequentially constructed in the space. A plurality of anti-shear devices perpendicular to the structural wall are arranged between the structural wall and the guard post. Each anti-shear device comprises a stress component and a waterproof component. Each stress component comprises profile steel. The profile steel is perpendicularly inserted into the structural wall. One end of the profile steel of each stress component is welded to an end plate connected with an embedded steel plate of the guard post, and the other end of the profile steel of each stress component is welded to an anti-shear nail inserted into the structural wall. Each waterproof component comprises a steel pipe and a special-shaped waterproof coil. Each steel pipe is arranged on the outer ring of the corresponding profile steel in a sleeving manner, one end of each steel pipe is welded to the corresponding end plate, and the other end of each steel pipe is inserted into the structural wall and wrapped by the corresponding special-shaped waterproof coil.