Energy internet is the key to achieve the energy reform goals in China, and the energy storage technology is one of the key technologies of energy internet, which has received spread attention. There exist various kinds of energy resources in the energy internet system, and different kinds of energy storage technologies are necessary to restore energy. Based on the analysis of principles and characteristics of energy storage technologies, the goals that hybrid energy storage systems need to achieve are presented. The energy demands of energy storage system are declared, and the necessity of the hybrid energy storage configuration is presented. Base on this, the coordinated capacity optimization method of hybrid energy storage system is presented and the efficiency and accuracy is verified through the case simulation.