To build a new energy system is the key towards China's goal of carbon emissions peak and achieving carbon neutrality. The new energy system will reshape the conventional energy system in an integrated and revolutionary way. It will not only bring about major changes in energy production, utilization and consumption, as well as emissions of greenhouse gas (GHG) and local pollutants, but also have profound implications on technological innovation and economic development. Based on quantitative and systematic analysis, this study depicts the energy system by 2030 and by 2060, analyzes the impacts of the energy system on economic and social development, studies and judges the key risk points, and proposes the path and policy system for building a new energy system. This is an open access book.