The shortage of energy restricts the economical development of the remote areas and islands where the grid extension is expensive and difficult. Moreover， fuel price has been increasing drastically over the past decades， as a result， stand-alone renewable energy hybrid power generation stations have become a solution to solve the energy shortage difficulties in those areas. Hybrid energy power generation becomes more popular all over the world. A renewable energy hybrid power generation system including wind energy， solar energy and wave energy， was established in Dangan Island， Zhuhai City by Guangzhou Institute of Energy Conversion， Chinese Academy of Sciences， and is supplying power for the residents in the island. A desalination plant in the system is standing by as a load， which will be switched on when the power is excess， or when there is a shortage for fresh water supplies. The excess power can be used to desalinate sea water to supply fresh water for the island. An energy management system of hybrid energy power generation based on a main-subordinate unit is designed to manage energy more effectively. This system samples the voltage and the current signal of battery， assesses the status of the battery， controls the energy flow， and sends massages to the persons concerned by a GSM module（TC35i）. The running results show that the energy management system increases the utilization of renewable energy， and extends the service life of the batteries. It also provides a reliable guarantee for the efficient and stable operation of the stand-alone system.