In order to study the effects of different catalytic walls on combustion characteristics, the premixed catalytic combustion characteristics of methane/air in microcombustor are studied. It lays the foundation for the combustion technology of hydrocarbonfuel in microengine. Numerical simulation of flow and catalytic combustion in microcombustor was done by using laminar finiterate and secondorder upwind discretization methods. The results show that when wall temperature，CH4/O2 mole ratio and methane mass flow rate change, the influence of lower catalytic wall on the methane catalytic combustion efficiency is biggest, followed by side catalytic wall, the smallest is upper catalytic wall. The methane catalytic combustion efficiency unit area of lower catalytic wall is about three times of that of upper catalytic wall. The utilization of catalyst on lower catalytic wall is maximal . Therefore, when coating catalyst, the quantity of katalyst on lower catalytic wall should be appropriate more, moderate on the side catalytic wall, as little as possible on the upper catalytic wall. The influence disciplinarian and contribution rate of different catalytic wall on methane combustion have been gained. The optimized strategy of catalyst coating was put forward and reduced the cost of catalytic combustion.