Dielectric loss is one of the important indexes to evaluate the insulation state of power cables. As the current emerging detection voltage, the oscillating wave voltage has a good equivalence with the power frequency AC voltage, and has a wide range of applications in the field of partial discharge detection. However, the dielectric loss measurement has not been carried out in depth, which has limitations for the integrated detection of insulation status. In order to solve the problem of current limitations, a cable dielectric loss measurement method based on the oscillating wave test technology is proposed. During each operation of the oscillating wave test system, the voltage or voltage-current data of the cable sample are collected, and then the waveform parametersare extracted through data post-processing to obtain accurate dielectric loss. At the same time, the two measurement methods are compared and the field error is analyzed, and the dielectric loss angle measurement method based on the oscillating wave voltage and current waveform has high accuracy and practicability, and a method to solve the problem of zero drift is proposed. Finally, simulation and experimental results verify the feasibility and effectiveness of the method.