The invention relates to an improved suture technique enhanced foam sandwich hat stiffened wall panel structure and a forming method thereof, belonging to the technical field of fiber composite enhancement. The foam sandwich hat stiffened wall panel structure is characterized in that the suture technique is used for the foam sandwich hat stiffened wall panel and is used for improving the strength and stiffness of the hat stiffened wall panel. The method comprises the following steps: firstly, laying hat ribs and skin on a stiffened wall panel mould; secondly, perforating a foam core material along the thickness direction according to the pre-designed perforation pattern (the perforation directions of front and rear rows are symmetric along the vertical foam centerline) in a foam sandwich; thirdly, suturing upper and lower panels and the core material with a suture together; finally, combining and packaging the hat ribs, and solidifying. The strength, stiffness and stability of the composite hat stiffened wall panel structure are obviously improved. According to the bearing capacity required by the enhanced hat stiffened wall panel, the suture parameter meeting the requirement can be designed. The suture foam sandwich structure provided by the invention has the advantages of strong bearing capacity, simple manufacturing process, high structural efficiency and low manufacturing and maintenance cost.