：For the problem of complicated structure,low real-time and establishing a training set of traditional positioning system,a rectangular strain rosette structure consists of three fiber Bragg gratings (FBG) is adopted to detect impact load. Under the plane strain,transverse effect correction factor model and the strain of decoupling model are established,which proves that the rectangular strain rosette structure used for localization is not influenced by the transverse effect. At the same time,based on the four edges simply supported plate structure,a novel method is proposed for determining impact load. A principal strain direction of the impact point is respectively measured by two groups of different position of FBG rectangular strain rosette structures,and their intersection point determines the impact source coordinates. Axial strain measured by FBG sensors is compensated by transverse effect correction,which combines with four edges simply supported plate immunity curve and FBG positioning coordinates for determining impact load. Experiments show that the localization accuracy is within 2.9 cm,real-time localization around 1 ms,error of impact load prediction with 3 N. A practical and feasible method is provided for load detection on impact load platform.