Energy plays a driving role in socio-economic development arena; poverty reduction and improvement of the quality of life. Conversion of animal waste to biogas energy to replace traditional fuel and use of the slurry as a fertilizer is the current focus of the national biogas program of Ethiopia (NBP 2013). This paper presents the experimental results of the anaerobic digestion of cactus (Opuntia ficus-indica) (L.) Mill. The total solid (TS), volatile solid (VS), fixed solid (FS) and the C:N ratio of the feed stock (cactus) had been determined before the anaerobic digestion process began and then estimation of biogas production and methane content of each of the treatments, T1 (