Abstract: The effects of three flow patterns (plug, parabolic, and jet) on heat transfer and hydrocarbon steam reforming process in a top-firing tubular reformer have been studied based on the calculation of heat transfer by zone method. With mathematical simulation, it is shown that for the flow patterns, though the temperature field and tube wall heat flux distribution in the reformer are differnt, there are no more effects on the simulation results of the reforming process, the results agree well with the data measured from an actual reformer. The resistances of heat transfer inside & Outside tube are given quantitatively.