The reaction mechanism on surface of BaCo0.7Fe0.2Nb0.1O3-delta membrane for reforming coal-gas was studied. The effects of metal particle on membrane surface were concluded. 'Activation mechanism' was proposed to be the key for enhancing oxygen permeation of membrane; while the catalyst-bed only takes charge of the reforming reaction. Though not as important as 'activation mechanism', the 'space charge mechanism' still affects the oxygen permeation of membrane. According to these mechanisms, the new design and surface-modifying strategy of membrane reactor were proposed. (C) 2010 Elsevier B.V. All rights reserved.