Abstract: The service life and repair costs of electrolyzer are related to the economic benefits of the entire electrolytic aluminium industry, which is a technical issues that cannot be ignored. In order to repair the damaged electrolyzer in time and prolong the service life of the electrolyzer, the impact echo method is proposed to evaluate the damaged condition of the electrolyzer. Firstly, the influence of the characteristics of impact echo excitation source on the stress wave pulse width and stress peak is discussed by numerical simulation. The results show that there are a linear correlation between the diameter of the exciting source (D) and the pulse width (t_c) of stress wave (t_c= 0.004D), and an exponential correlation between the diameter of the exciting source (D) and the peak stress (P) (P=2e⁸D^{1.928 8}). However, the impact velocity (v) does not change the pulse width (t_c), but there is a linear correlation between the impact velocity (v) and the peak stress P (P = 0.0751v-0.068 6). Then, based on the results of numerical simulation, the impact echo method is used to detect the cathode steel bar in the damaged electrolyzer. Through the time-frequency analysis of the detection results, the damage condition and position of the cathode steel bar are obtained, and the analysis results are compared with the damage condition of the real cathode steel bar after grooving. The results show that the impact echo method can be used to locate the damaged parts of the electrolyzer, which can provide a reference for the life evaluation and repair of the electrolyzer.