In order to solve the problem of not being able to obtain the length at any position on the cable path from the first end, the project team developed a device of distance measuring which to realize the detection of the length of buried cables. By injecting the traveling wave signals into the cable sheath or core, two master and slave traveling wave detection devices are used to synchronously collect the traveling wave signals propagating on the cable path, and calculate the length of the cable at any position based on the traveling wave time difference. Meanwhile, the effectiveness and feasibility of the device was verified through field tests on the cable, and it can be promoted and used in relevant operation and maintenance units carrying out fault finding on 10kV cables in China.