In this paper, in view of corrosion damage in reinforced concrete, an electrochemical method is applied to accelerate corrosion tests of reinforced concrete trabeculars in different degrees, and ultrasonic guided wave tests are carried out on them respectively. Through the first wave energy analysis, the signal energy changes before and after corrosion are obtained. The original signal was analyzed by wavelet packet respectively, and the wavelet packet energy spectrum of each corrosion stage was obtained. The damage degree of the structure was diagnosed by the change of the energy distribution of each frequency band signal. The time-frequency curve of the signal, waveform characteristics, damage categories and frequency distribution of each damage stage are obtained by wavelet packet analysis.