Abstract: In order to evaluate the greenhouse gas (GHG) emission reductions of the bundling small scale clean development mechanism (CDM) projects in livestock farms, one bundling small scale livestock CDM project in Hubei province of China was studied. Using methodology AMS-III.D and AMS-I.D, which were approved by executive board (EB) of clean development mechanism (CDM) under United Nation Framework Convention on Climate Change, greenhouse gas emission reduction by improvement of pig manure management and biogas utilization for electricity on seven pig farms which are bundled for a CDM project was analyzed. Additional cost of bundling was also evaluated. It has been proved that the advanced anaerobic system could reduce greenhouse gas emission by 86.5%，which was estimated to be 37 443.7 t CO2 equivalent a year of this bundling project. The cost of each head of pigs in bandting development compared to the non-bundling development was reduced by 49.71%. This study play a guiding role for similar project development.