Intelligent network is an important mean to achieve energy saving and promote renewable energy develop. With the technology of power electronics, IT, communications continuing to evolve, the smart grid will be an important direction of the electric power industry development. It has been always said that Smart Grid communication should be reliable but this has not been clarified why and how. Although there has been some basic analysis and works but a thorough reliability study of any proposed architecture is still missing. Briefly, the goal of this project is to demonstrate a reliability and security assessment process. To do so, we utilized the most common methods (Reliability Block Diagram and fault tree) to analyze the system using powerful tool, BlockSim7.