Abstract: Based on neutral point arc suppression coil series damping resistance is grounded, a method of real-time measurement for leakage current in distribution network was introduced. A accurate measurement of leakage current in distribution network by injected signal is proposed. A specific frequency current signal which is not power frequency was injected into the distribution network through zero-sequence voltage transformer in distribution network. The returned voltage signal was measured by the internal voltage transformer of arc suppression coil. And the leakage conductance in distribution network was calculated. The simulation results showed that the measurement accuracy of the proposed method is high, the measurement process does not need to change the primary-side wiring of the distribution network and does not affect the normal operation of the distribution network, which can eliminate the influence of the damping resistor and the internal resistance of the voltage transformer.