Abstract: In order to solve the problem of leakage localization of anti-seepage layer in landfill before operation, an ultrasonic leakage detection method of high density polyethylene (HDPE) membrane is proposed. According to the characteristics of energy attenuation caused by the ultrasonic wave scattering at the leakage location, the wavelet analysis is used to extract the ultrasonic energy density parameters with or without leakage. The damage index is defined according to the parameters in the two states, and the leakage location of HDPE film is determined by combining damage imaging. In the experiment, a detection network is formed by the piezoelectric plate laid on the surface of HDPE film, and the piezoelectric plate is controlled by any waveform generator to generate specific ultrasonic signal. The detection area is scanned by the way of “one emitting and multiple receiving”. The experimental results show that the damage index of HDPE membrane with or without leakage has a difference of at least 100 times. The localization of simulated leakage is realized. The maximum localization error of single leakage point is 8.4mm, and the maximum localization error of double leakage points is 13.7 mm. The localization error is within the acceptable range.