The characteristics of micro-combustion are easy flameout，great heat loss，incomplete combustion and low efficiency. The premixed catalytic combustion of methane can improve combustion stability and combustion efficiency. The premixed catalytic combustion characteristics of methane in micro-combustor were studied. It lays the foundation for the combustion technology of hydrocarbon-fuel in micro-engine. Numerical investigation of catalytic combustion，flow and heat transfer in micro-combustor was made by using laminar finite-rate and second-order upwind discretization model. The results showed that the mass flow rate of methane and excess air coefficient had an influence on catalytic combustion efficiency. Wall temperature was a primary factor of catalytic combustion efficiency. The optimal coefficient of excess air was related to the mass flow rate of methane and wall temperature. To improve micro catalytic combustion efficiency，an appropriate oxygen-enriched（or fuel-rich）combustion method should be selected according to wall temperature. Under the thermal boundary condition of constant wall temperature，catalytic combustion mostly happened on the downside wall of combustion-chamber.