Abstract: Based on the wavelet transform and its multiscale decompositions, we will construct a kind of wavelet energy accumulator, by which the energy on decomposition all different scales. As an application, an algorithm is developed that weak signal detection on wavelet energy accumulation. In this paper, we design a piece of simulation program and do many of radar signal detection simulation experiments with pulse and different simulation conditions (on the background of white noise and color noise). Simulation results indicate that weak signal detection is very successful depending on wavelet energy accumulation.