This paper presents a dynamic droop control scheme for islanded microgrids dominated by intermittent renewable energy sources, which is able to perform desirable power sharing in the presence of renewable energy source fluctuation. First, allowable maximum power points of wind generator and PV generator are calculated in different wind speed and insolation ranges. Then, piecewise droop relationships between distributed generators are built. Finally, the dynamic droop control is proposed to perform power sharing according to wind speed and sunlight information from local sensors. The dynamic droop controller of each DG unit is activated through local logic variable inferred by wind speed and solar insolation information. Simulation results are given for validating the droop control scheme. The proposed dynamic droop scheme preserves the advantage of conventional droop control method, and provides flexibility and effectiveness in the presence of the renewable energy sources fluctuation.