Improper waste management in industry and livestock sectors will contribute to the increase in greenhouse gas emissions. Anaerobic digestion technology is one of many technologies to convert waste to energy. Anaerobic digestion is claimed to reduce greenhouse gas emissions to the atmosphere. The research aimed to find the most optimal composition for anaerobic co-digestion of dairy cattle manure and sludge of domestic wastewater treatment plants (WWTP). The composition of the substrates used in this study had the ratio of dairy cattle manure and sludge and control with the composition of dairy cattle manure and water (P0) as a comparison. Anaerobic digestion was processed for 40 days, and gas sampling was conducted every 10 days until the 40th day to analyze methane composition using Gas Chromatography (GC). Other variables of the test data were pH, water content, temperature, organic material content, and C/N ratio. The data obtained was analyzed with one-way ANOVA with a significant 5%. In general, the relationship between total CH4 emissions produced and water content, pH, temperature, and C/N was positively correlated and had a significant effect on each treatment. Treatment of anaerobic co-digestion with sludge from domestic WWTP as raw material in biogas production had no significant effect on increasing methane production. The best biogas production was performed by control (P0). The results showed that the process of co-digestion of dairy cattle manure and sludge from domestic WWTP into biogas can suppress the emission of CH4 gases that are released freely and can reduce greenhouse gas emissions in the atmosphere as well as other emissions.