For the islanded microgrid based on wind and wave energy, a coordinated frequency control strategy with Battery Energy Storage System(BESS)and controllable load is proposed to improve the frequency stability. A novel droop controller is implemented in BESS to achieve primary frequency regulation. In the proposed droop strategy, the stable running point and droop gain are dynamically adjusted according to thestate of charge(SOC), to prevent the over-limitation of frequency, over charge and discharge of BESS. Moreover, controllable loads such as seawater desalination is served as a secondary frequency regulator. And then, frequency error is sent into PI controller to acquire the power reference of controllable loads so that the stable frequency error can be eliminated. Finally, the simulating model of islanded microgrid is built with Matlab/Simulinkand simulation verification is performed underdifferent operating scenarios. The results show that the coordinated frequency control strategy can effectively maintain the power balance and frequency stability of the islanded microgrid.