The existing single-phase grounding fault protection method for distribution network cannot be reliably started when a high resistance grounding fault occurs. The results of fault phase selection and fault line selection are greatly affected by three-phase imbalance. To solve the above problem, a new method of single-phase grounding fault protection for a resonant grounding distribution network based on unbalanced overvoltage dynamic suppression is proposed. Based on the dynamic suppression of a three-phase unbalanced overvoltage, the characteristics of injection current and feeder zero sequence current before and after the phase-to-ground fault are analyzed. Given the characteristics of the injection current variation, the dynamic perception criterion of grounding fault is constructed. The fault phase selection and the transition resistance calculation are carried out by adopting the phase and root-mean-square value of the variation respectively and the fault line selection is carried out by comparing the amplitude of the zero-sequence current variation for each feeder. The PSCAD/EMTDC simulation results show that the proposed method can be started accurately for a high resistance ground fault, and the results of phase selection and line selection are not affected by the three-phase imbalance and the capacitance to ground. This work is supported by the Key Program of the National Natural Science Foundation of China (No. 51737002 and No. 51807012).