Landfill gas is a type of methane-rich biogas which supplies renewable resources for clean fuels production. In this paper, the characteristics and optimum conditions of simulated landfill gas and biogas reforming reactions for H-2 production are investigated. The temperature, varied from 373.15 K to 1273.15 K, and pressure, varied from 1.013 bar to 40.013 bar, applied for the reforming system are evaluated. In addition, the effect of steam concentration, traces of hydrocarbons, and the ratio of C/H/O are analyzed using thermodynamic theories. Both the calculation and analyzed results demonstrate that the reforming system is primarily comprised of endothermic reactions. It favors lower pressure and higher temperature. Traces of hydrocarbons would result in a slight increase to CO for this system. A high ratio Of CO2 would result in more production of CO in the reforming process. Preliminary experiments on fuel cells indicate this gas-reforming simulation is an elementary theory for fuel supply.