This paper takes town gas premixed combustion within ported ceramic plaque as studying object. An experiment is carried upon the plaque to test the surface temperature and CO emission under different heat flow. Based on analyzing the conductive, convective and radiant heat transfer and combustion process within the plaque, a steady mathematic model is established successfully. The flame temperature profiles within the plaque and surface temperature of the plaque under various heat flow is predicted numerically, which is compared with the experimental datas.