The invention provides an energy utilization system of organic wastes with zero emission of carbon dioxide, which organically combines anaerobic fermentation hydrogen production, methane fermentation, CO2 absorption, microalgae fixation CO2, biogas liquid treatment and energy grass planting. The system is suitable for treating various types of organic wastes, can be applied to the treatment of agricultural organic wastes, industrial organic wastes, domestic organic wastes, slurry and the like, and the industries, such as new energy development. Through the application of the invention, the specific application demonstration of recycling economy can be carried out, clean energy is obtained while eliminating environmental pollution, no greenhouse gas emits in the process, and the triple effects of wastes treatment, production of clean and renewable energy sources and reduction of carbon dioxide emission can be realized.