The problem of new and old hybrid power cable fault precision location is researched. The length error is caused by the traveling wave velocity discontinuity. In order to solve this difficulty, the way of the signal traveling wave velocity section analysis is put forward. The transmission characteristics of pulse signal in the new and old power cable is researched, and the wavelet modulus maxima is used to search the abrupt change points of the pulse to locate the cable fault. Finally, the new and old power hybrid cable fault location model is simulated in the simulation platform. The wave velocity optimization calculation and the fault location are realized, and the result error is analyzed. The experimental results show that the pulse wave velocity section analysis can improve the precision of pulse location and it also can achieve good results. At the same time, this method can be generalized to other occasions.