With the rapid increase and wide usage of distributed generation (DG), isolated island detection becomes an unignorable research problem. At present, most of the research on island detection focuses on the isolated island situation of the single inverter grid connection. The study on the island detection of multiinverter is relatively scarce. This paper analyzes the inverter interactions in multiinverter grid connection. In view of the problem that the line impedance angle between the inverters produces a dilution effect on the disturbance signal and leads to the failure of island detection, this paper proposes a sinusoidal droop control (SDC) island detection method. The nondetection zone (NDZ) of the method and its impact on the power quality of the power grid is analyzed. Experimental simulation results in Matlab/Simulink show that this method can effectively reduce the NDZ, reduce the impact of power quality to the grid, and can effectively avoid the dilution effect of line impedance NDZ.