Abstract: In order to accurately detect incipient faults and perceive the status of distribution network lines in time, according to the diversity of fault manifestations, and taking into account characteristics of phase voltage, phase current, zero sequence voltage and zero sequence current, the grounded incipient fault detection algorithm based on compound criterion is proposed, and the adaptability of common trigger detection criterion to incipient fault occurred in such grounding system is analyzed in this paper. The algorithm can be adopted to solve the problem that existing incipient fault detection algorithms neglect the diversity of incipient fault in non-solidly grounding system, and to realize the sensitive and accurate detection of "single-phase grounding type" and "two-point grounding in two phases type" incipient fault occurred in such system. Simulation data based on PSCAD/EMTDC and field data verify the correctness and availability of this method. Then the detection ability of this method and its effectiveness critical curve under different fault resistance conditions are analyzed.