Abstract: In order to solve the problem of multi-distributed generation (DG) islanding detection failure caused by dilution effect, a new multi-DG islanding detection method based on zero-sequence voltage positive feedback control is proposed. According to the phase relationship between the three-phase voltage and the zero-sequence voltage at the point of common coupling of the DG, in the method, the sinusoidal pulse width modulation technology is adopted to control the phase of the voltage at the output side of the inverter to realize the positive feedback disturbance of the zero-sequence voltage amplitude. The voltages of the grid-connected points are the same, therefore, the phase relationship between the zero-sequence voltage and the phase voltage can be used to control the amount of disturbance injected by each DG into the grid-connected point with the same disturbance direction, thereby eliminating the dilution effect caused by the opposite direction of disturbance of each DG. MATLAB/Simulink for simulating and RTBOX for physical experiment results show that the dilution effect can be eliminated and multiple DG islands can be detected by this method. The proposed method can be adopted to reduce the occurrence probability of "reverse power transmission" caused by DG access, and to ensure the personal safety of maintenance personnel.