Abstract: Based on the series oscillating principle by using of cable capacitance and inductance winding, Oscillating wave test system (OWTS) can be used to excite PD signal on cable defect during the polarity of oscillating voltage change with the purpose of detecting the signal through high frequency coupler. Two kinds of defects in cable joints (misuse insulated tape, consisting water film) are studied by using of OWTS. The results show that OWTS is more effective in detecting misuse insulated tape than other defects, which is verified by electric field simulation based on Finite Element Method (FEM). At the same time, the substitute of grid\|connected experiment for 10kV XLPE power cables by OWTS need to be further studied.