For the past few years, as the consciousness of carbon reduction and environmental protection has been rising, power must be used efficiently. The energy management system, therefore, has become an extremely important role in reducing use of energy. Through the electrical energy management system, we can improve the efficiency of electric power use, and also achieve the goals of safety and continuously reducing electrical requirements, knowing all the status and avoiding overuse. Through the instantaneously collecting information of power and electric meter, the system will provide the best estimated demanding quantity, warning of electric use and future methods for power saving. It is a practical and efficient system.