A miniature double-layer disc-combustor with porous medium and Swiss-roll preheated channel, which can act as a miniature heat source, is proposed in this study, and the lean premixed flame behavior and thermal performance of 60% H₂-40% CH₄-air mixture in the case of various combustion chamber heights in it are investigated by the means of the experiment. The experimental results indicate that the effect of the combustion chamber height on the blow-off limit is insignificant. In the case of a constant combustion chamber height, the blow-off limit enlarges with the decreased Reynolds number, which is induced by a decreased stretch effect of incoming fresh mixture on the flame front. The lean premixed flames present the circle-shape in the case of the majority of operating conditions. At a large Reynolds number, the maximum and mean values of the upper wall temperature profiles of the combustor both increase with the increased equivalence ratio. In addition, they present the similar change rules with the increased Reynolds number at a constant equivalence ratio. At a small Reynolds number, the effects of equivalence ratio on the maximum and mean values of the upper wall temperature profiles are insignificant. The present work provides theoretical bases for the engineering application of lean premixed combustion technology which can realize clean and efficient combustion.