The aim of this work is to analyze nature gas-fed internal reforming solid oxide fuel cell system. The system consists of ejector, heater exchanger, solid oxide fuel cell (anode and cathode) and afterburner, and models by Aspen Plus(TM). A parametric analysis also performed to evaluate the effect of various parameters such as the current density, the operating temperature, the operating pressure, the fuel utilization factor, the air utilization factor and the S/C ratio on system performance.