The purpose of this paper is to investigate the optimal operating condition for the hydrogen production by biogas reforming using the plasmatron induced thermal plasma. The component ratio of biogas(CH4/CO2) produced by anaerobic digestion reactor were 1.03, 1.28, 2.12, respectively. And the reforming experiment was performed. To improve hydrogen production and methane conversion rates, parametric screening studies were conducted, in which there are the variations of biogas flow ratio(biogas/TFR: total flow rate), vapor flow ratio(H2O/TFR: total flow rate) and input power. When the variations of biogas flow ratio, vapor flow ratio and input power were 0.32~0.37, 0.36~0.42, and 8 kW, respectively, the methance conversion reached its optimal operating condition, or 81.3~89.6％. Under the condition mentioned above, the wet basis concentrations of the synthetic gas were H2 27.11~40.23％, CO 14.31~18.61％. The hydrogen yield and the conversion rate of energy were 40.6~61％, 30.5~54.4％, respectively, the ratio of hydrogen to carbon monoxide(H2/CO) was 1.89~2.16.