With the rapid development of communication technology and electric power industry, cables have been widely used. The demand for cables in various industries has risen sharply, so a variety of cables have appeared in the market. After a large number of cables are used, cable break failures occur frequently. In addition, most cables are installed in the special environment of high altitude or underground. Without professional testing equipment, line maintenance personnel can hardly find the fault location. Based on this, an efficient cable breakpoint location method is proposed, and the modulus maximum detection algorithm based on wavelet transform is studied to realize the cable breakpoint location. The wavelet threshold de-noising technology is used to remove the noise in the transmission signal and reflection signal collected by the system. By comparing the results of different wavelet decomposition, the optimal wavelet basis function is selected, and the modulus maximum sequence of the wavelet coefficients obtained after wavelet decomposition is calculated, then the time difference between the transmission pulse and the reflection pulse can be detected, and the location of the cable breakpoint can be further determined. The existing cables in the laboratory are tested for many times, and the actual test results are analyzed, which can meet the technical requirements of cable breakpoint detection.