Abstract: The coupling of high power microwave into electrical systems, such as airplane, cars, ships, is very complicated. Furthermore, if the incoming wavelength is much smaller compared to enclosure size of target system, the coupling properties of the system depend on its size and shape, the geometry of apertures, and the frequency of the incoming wave. In the short wavelength limit, the nature of the inside electromagnetic field is extremely sensitive to subtle changes in frequency, the shape of the enclosure, and the orientation of the internal devices or cables. At present, even with the fast and powerful computers that utilize efficient 3-D numerical analysis code, addressing this problem is a great challenge because of the numerous CPU resources and computational time. Thus, statistical electromagnetic methods are more appropriate. The stochastic topology approach is a novel statistical method for analyzing system level electromagnetic effects, which combines the BLT topology theory and the random coupling model. This method is able to predict the statistical distribution of induced voltages or currents on components within a system that consists of multiple cavities when excited by short-wavelength interference, such as high power microwave (HPM). Thereby, the probability that the components be disturbed or damaged will be predicted with the threshold data. The general theoretical approach is introduced, and our work on experiments to verify the feasibility and accuracy of this method is presented.