Abstract: Choosing suitable biogas inoculum is an effective way to improve the methane content,the fresh cow dung and dry weeds as the substrate, four kinds of inoculum were inoculated and incubated at 4℃ for researching different inoculum effect on biogas methane content.The results showed that the highest methane content was 52.66% and 48.04% in aerogenesis respectively inoculated Gen river mud samples grouped A and Huolin river mud samples grouped B, the highest methane content was 14.45% inoculated group C biogas slurry at cold acclimation; the highest methane content was 20.08% inoculated group D biogas slurry with activated carbons at cold acclimation; Different biogas inoculums had significant effect on the methane content.