A system energy efficiency controller in a smart energy network, a control method thereof, and a control method for a terminal device. The system energy efficiency controller includes a control decision module, a storage module, a power clock module, an internal communication module, and an external communication module. The storage module is connected to the control decision module, and stores temporary and permanent information data in the operation process of the storage system. The power clock module provides an internal clock, achieving timing synchronization of processors on the controller. The internal communication module provides two-way communication between the system energy efficiency controller and control implementation units of multiple terminal devices. The external communication module provides two-way communication between the system energy efficiency controller and a local optimizer. The multiple terminal devices include at least one of the terminal devices for the stages of energy production, storage, application and regeneration.