Abstract: In order to solve problems that power parameters of low-frequency superposition method have an effect on detection accuracy of insulation resistance in XLPE cable insulation detection, it deeply studied the relationship between the power parameters of low-frequency superposition and detection accuracy or fault selection of XLPE cable insulation. Then it did the experiment and simulation considering the amplitude and frequency of power. The results showed that resistance current components and detection accuracy would be gradually increased with the reduction of power amplitude at a certain frequency; under a certain voltage, detection accuracy of cable insulation was increased and the frequency superposition method had a better fault selectivity while the power frequency decreased.