Oxytetracycline is one of the tetracycline antibiotics for feeding pig or cow, tetracycline antibiotics are the most widely used in animals and veterinary medicine as growth promoters and antibacterial drugs and it can pose potential threat to animal and human health in the world. The aim of this study was to examined evaluation effective the difference of oxytetracycline concentration volumes in anaerobic batch digestion of fresh pig manure, which the experiment was carried out in three groups following as blank, control and sample groups, respectively, and each experiment groups were three replications over a period of time about 30 days and the same conditional temperature at 30 +/- 1 degrees C. The experimental results showed that all the sample and control groups significantly increased the high peak of biogas volume by starting in the first and seventh day, by the end of the day of eighth day, fermentation slightly decreased the volume of biogas production. The volume of oxytetracycline concentration in the range between 10 and 50 mg/kg was capable of high production of biogas by volumes of 2,218 to 2,817 ml, and methane contents of biogas produced were 45.96-49.69%, respectively. And from 100 to 500 mg/kg of oxytetracycline concentration volumes, it seemed to be moderate inhibition of anaerobic microbial activity, but the severe inhibition occurred when the concentration of oxytetracycline volume reached in the range of 1,000-2,000 mg/kg by decreasing the biogas production from 1,996 to 419 ml, respectively (38.10% and 33.89% of methane values). Unlike the generally believed adverse effect of tetracycline antibiotics, the results of this study demonstrated the favorable role of Oxytetracycline (OTC) in biogas production and thus provide new insights into their true biogas project or environmental impacts.