A computer simulation was conducted for heat and momentum transfer in a roller kiln. Time-averaged Navier-Stokes equation conjugated with energy balance equation was numerically solved to predict the temperature distribution and fluid flow field in the roller kiln. A computer simulation was performed for a roller kiln for three cases. Firstly, when there are no ceramic materials in the roller kiln, the effect of natural convection was studied on the temperature distribution and fluid flow field. From the result, it was observed that air takes the heat of wall away from the roller kiln by natural convection and the heat was not transferred effectively. Secondly, with ceramic materials temperature difference of ceramic material from the borrom to the top of a ceramic material was about 255K in 5th zone and this is because the heat is transferred from the surface of a ceramic material to flowing air with relatively low temperature. Finally, we considered effect of radiation heat transfer. Temperature difference of ceramic material in 5th zone was about 300 K, due to radiation heat transfer on the ceramic material surfaces.