Abstract-Methane Steam Reforming(MSR) is a catalytic process in which methane is reacted with a water gas to produce hydrogen and carbon dioxide gases. Many experimental and simulation studies have been assumed to be an isothermal condition using a packed-bed inert membrane reactor(PBIMR). However, the flow fields of inside the reactor are complex and the temperature gradient also occurs because of the catalyst particles packed in the reactor. This study suggests a new model considering heat transfer at the reactor wall and pressure drop inside the reactor. The model applies to the MSR reaction using PBIMR. Results are compared with the published experimental and simulation data. The simulation results suggested in the study shows better agreement than the simple model with constant temperature assumption, for both cases of conventional packed-bed reactor and PBIMR. In addition, the effects of H₂O/CH₄, flow rate of sweep gas and particle diameter of catalyst on the methane conversion are investigated. A consideration of heat transfer at the wall of permeation side is remained for further study.