As a new technology to alleviate energy crisis and environmental pollution, producing hydrogen by water electrolysis using wind and solar energy is becoming popular recently. However, due to the randomness and intermittence of renewable energy, the slow dynamic response, the limitation of input power of the electrolyzer for hydrogen production and so on, new operation control technology has to be used to coordinate the sources and loads. In this paper, a simple and optimized operation control strategy is proposed for the wind-solar-energy storage-dominated islanded microgrid used for hydrogen production. The optimal operation is realized by simply regulating the AC-bus voltage of the microgrid system and the operation principle is elaborated on first. Afterward, a simulation model, which includes 2 MW wind turbine, 375 kW PV system, 315 kW energy storage system, 24.2 kW PEM and 785.2 kW alkaline electrolyzer, is established. The validity of the proposed method is verified by simulation results.