Abstract: In order to study greenhouse gas (GHG) emission reductions and their energy environmental benefits generated by the use of rural household biogas in the impoverished rural areas in China, rural low- income household biogas project of Liang Shan Prefecture in Sichuan Province was researched, which involved 35656 households biogas digesters from 14 counties. GHG emission reduction of rural household biogas project was estimated by using methodologies of AMS-III.R and AMS-I.C of clean development mechanism (CDM), and its energy environmental benefits were analyzed. Results showed that with the use of rural household biogas digester, it could reduce GHG emission range from 1.8 t CO₂ e to 2.5 t CO₂ e for each household, and 72898.2 t CO₂ e for the overall project annually. Meanwhile, it could bring direct savings of about 21600 t rawcoal and about 6.48 million yuan coal purchase costs annually, direct output of about 19,780,000 m3 biogas clean energy annually, direct reduction of SO2 emissions about 288440 kg, NOx emissions about 31320 kg, soot emissions about 15120 kg annually. It indicated that with the promotion of rural household biogas project, on the one hand, it could realize CH4 emission reduction from the pigs manure management practices and CO₂ emission reduction from the use of renewable energy of biogas instead of raw coal; on the other hand, it could generate considerable energy and environmental benefits. In addition, using CDM methodologies to estimate GHG emission reduction can provide a quantitative basis and reference for monitoring, reporting, verification (MRV) of the GHG emissions of the agricultural sector.