The islanded microgrid adopts droop control to make inverters share load power according to the capacity proportion of distributed generation (DG), so as to prevent the DG from overload, light load, or generating power circulation. However, the power sharing effect of inverters is related to both the line impedance and the changes in the actual capacity of DG. To solve this problem, an improved droop control strategy considering the randomly changing output from DG is proposed. This strategy adopts two-layer control, in which the outer-layer control eliminates the influence of line impedance in a rated working state. Under changes in the operation condition, the proportion of changed capacity of DG is obtained according to the changes in the voltage of DC bus in a two-stage inverter, and the reference values of power and voltage in a non-rated working state are formulated. In the inner-layer, an improved droop control is adopted to adjust the coefficient of droop control to make the inverters work under the reference value of voltage. Finally, the output from inverters is adjusted to ensure power balance. Simulation results verify the correctness and feasibility of the proposed strategy.