Abstract: Aimed at the errors in modeling and principle of traditional measurement methods for grounding parameters, an accurate measurement method for grounding parameters of neutral ungrounded distribution network based on feeder power is proposed. By adding a controllable voltage source to the neutral point to regulate the zero sequence voltage, the active and reactive power of each feeder line is obtained, and combining the relationship between feeder line power and grounding parameters, the accurate measurement of the conductance and capacitance parameters of each feeder and system to ground are achieved. Furthermore, a sensitive sensing method of single-phase grounding fault based on feeder power is proposed, which can accurately identify whether the bus and feeder of distribution network are in fault through the difference of power factor angle characteristics between fault and normal feeder. This method can effectively solve the measurement problem of system to ground parameters, realize the sensitive sensing of single-phase ground fault, and accurately distinguish the bus and feeder faults based on the mathematical relationship between feeder power and ground parameters, power factor angle. The proposed method is simulated and verified in PSCAD/EMTDC simulation environment and 10kV real distribution network experimental field. The analysis results show that the method has high measurement accuracy, strong fault perception ability and certain engineering application value.