Abstract: With offering clean energy, reducing rural environmental pollution, decreasing greenhouse gas emissions such as CO₂ and CH₄, and therefore moderating the tendency of the global warming, large and middle-scale biogas project is a key program to renewable energy construction in China. The greenhouse gas mitigation benefits of large and middle-scale biogas project from 1996 to 2005 were analyzed. The results show that the large and middle-scale biogas project can reduce the discharge of CO₂ 0.54×10⁶～1.51×10⁶ t and CH₄ 1.53×10⁵ t (CO₂ equivalent), and bring economic income of 1.16×10⁸～2.69×10⁸ Yuan(RMB) in 2005. According to Mid-and Long-Term Development Programming for Renewable Energy, the predicting results indicate that the CO₂ emission reduction of large and middle-scale biogas project can reach 0.56×10⁷～ 1.17×10⁷ t/a and 1.95×10⁷～5.99×10⁸ t/a, and CH₄ emission reduction can reach 1.79×10⁶ t/a and 6.28×10⁶ t/a, and the economic benefits are up to 0.17×10⁹～3.00×10¹⁰ Yuan/a and 0.41×10¹⁰～1.05×10¹⁰ Yuan/a in 2010 and 2020, respectively. The large and middle-scale biogas project construction is an effective measure to improve rural environment, reduce the discharge of greenhouse gas and relieve the tendency of the global warming in China.