As the scale of distribution network expands and the operation environment is complex and variable, the single-phase disconnection fault of arc suppression coil grounding system becomes more and more frequent. Due to the compensation function of arc suppression coil, the electricity quantity is weak when the disconnection fault occurs, so it is difficult to monitor the fault and construct the protection scheme. Aiming at the single-phase disconnection fault of the feeders of arc suppression coil system, Based on zero sequence admittance, a single-phase fault protection method for feeder of arc suppression coil grounding system is proposed in this paper. Firstly, the characteristics of the zero sequence current at the beginning of the line and the zero sequence voltage of the busbar are analyzed, Using the ratio of zero sequence current to zero sequence voltage to obtain zero sequence admittance, it is pointed out that the zero sequence admittance phase of non fault lines is in the first quadrant, while the zero sequence admittance phase of fault lines is in the second or third quadrant. Then, the zero sequence admittance of the faulty line in the case of arc suppression coil overcompensation is improved by multiplying the zero sequence admittance phase of the line by the corresponding symbol coefficient, which expands the difference between the zero sequence admittance phase pairs of the faulty line and the non faulty line. Based on the phase characteristics of the zero sequence admittance, a fault protection criterion is established. Finally, the reliability of the proposed method is verified by PSCAD/EMTDC simulation results.