In this study, the effect of different parameters (mixing speed, temperature, substrate/inoculation ratio) on the anaerobic digestion of cattle manure liquid fraction was analyzed and optimized with Taguchi method. As a result, it was concluded that mixing speed has an increase of 29% on methane gas production. Optimum operating conditions were determined as 120 rpm, 35 ˚C, and 1.5 S/I ratio. Under these conditions, 465 mL methane in 30 days was produced. 84% COD removal was provided. It has been observed that the liquid fraction of cattle manure can be decomposed under anaerobic conditions and transformed into energy rather than leaving it to the environment. It can be said that the farmers can efficiently digest the liquid part together with the municipal sewage sludge in the farms where solid-liquid separation is performed. Thus, environmental pollution will be prevented.