Anaerobic digestion is one the most efficient technologies in waste and wastewater management for producing renewable energy and reducing greenhouse gas emission from animal manure. In this experiment procedure was use duplicate samples and controls in different volumes of inoculum (10%, 20%, 30%, and 40%, respectively) were mixed with the same volume 10 g of casein, which the experimental results of the daily methane productions in duplicate samples were also slightly increased during the first day although out the final day of biodegradability process. The specific methane value in sample 40% was a highest methane volume about 86 ml/gVS when compared with the other samples (10%, 20% and 30%, respectively). However, the methane yield among samples was considerably lower than theoretical by comparison. Therefore, the differential volumes of inoculum used for a BMP test were influence the methane production of anaerobic batch digestion process, and these difference inoculum volumes were significantly effective or not were depending on the substrate used. This experimental study was to measure the methane production form different volumes of inoculum, and to evaluate the influence of inoculum by mixing 10g of casein as the substrate in BMP test processes.