It is difficult to solve the acoustic source localization problem of impact with the traditional methods since the propagation path of Lamb waves on the surface of porthole structure is no longer a linear path. To address this problem, a grid mapping probabilistic imaging localization method based on acoustic emission is proposed in this study. This method solves the nonlinear path problem of signal propagation by establishing a grid mapping model, and the corresponding theoretical time difference is obtained by calculating the fastest propagation path of signal at the grid nodes. Then the actual arrival time difference of signal is calculated by using the adaptive energy threshold method and the AIC method, and the probabilistic image is constructed by comparing the deviation of theoretical value with actual value to obtain the localization solution. The influence of band-hole structure on the propagation path of Lamb waves is analyzed by finite element simulation, and the basis of determining the signal propagation path is given. The feasibility of localization method is also verified by the localization experiments on 32 impact points, which provides an average absolute error of 1. 15 cm.