The major goal of this study is to design a model of the domestic communication satellite named by 2005SAT. The key features of 2005 SAT bus system have 3-axis stabilized platform for transfer orbit and on-orbit operations, main bus voltage with 42.5V and dual mode propulsion system. And also, the electrical subsystem of 2005SAT is designed to meet the performance requirements specified in bus system and subsystem specification during all expected spacecraft operations. The electrical bus system is designed to accommodate the communication payload requirements including the fifteen transponders and a 10 years design life. The basic design of electronic units and electrical interface of AOCS, EPS and TC&R subsystems for an ETB configuration is performed through the analysis and trade-off study of each subsystem.