The short-circuit current value of distribution network is small when high impedance grounding faults (HIGFs) occur,which cannot be detected tripped by the traditional over-current protection devices. If short-circuit cannot be tripped in time,it will lead to serious results. To solve the above problems,the fault components of microgrid in the operating conditions of HIGFs are analyzed. The phase differences characteristics between positive-sequence fault component of bus voltage and positive-sequence current fault components in the feeders are explained in detail. And based on the phase differences characteristics,the fault criterion for HIGFs in distribution network is proposed. Meanwhile,to overcome those problems caused by the imbalanced distribution network,the starting criterion is proposed. Based on the above fault criterion and the starting criterion,the new fault detection method is proposed. Finally,a medium distribution with the model of overhead lines is established in PSCAD/EMTDC,and simulation results verify the correctness of the fault detection method.