This book presents a succinct overview of research on China's Energy Efficiency as studied by the Center for Energy & Environmental Policy Research (CEEP), Beijing Institute of Technology (BIT). Energy efficiency, linking energy supply, demand and market, is crucial to the world's energy development. China consumes one fourth of the world's energy currently, however its per capital consumption is no more than half of that in OECD countries. This book provides a comprehensive treatment of the situation of China's energy development, proposes and summarizes the methodologies of energy efficiency measurement, and uses these methods to analyze the energy consumption at sectoral and provincial level, the impacts of economic structure on the energy macro-efficiency, the price elasticity of oil demand, and energy efficiency policies simulations. The book provides scientific support for researchers and policy makers dealing with energy efficiency.