Abstract: An airplane cable faults diagnosis method based on time-frequency domain reflection is proposed to solve the problems of being difficult to diagnose part faults,serial faults and after-junction faults because of weak echo signal and serious decay in the time domain reflection method.The time-frequency domain reflection method can diagnose faults more easily and improve the hit rates.In addition,the threshold de-noising method based on wavelet decomposition is utilized to eliminate the interference of noise and reduce the false alarm rates.The feasibility is verified and the comparison with time domain reflection method is processed by experiments.The results show that the time-frequency domain reflection method is better than the time domain reflection method in the aspects of hit rates and false alarm rates.