A triple-layer composite membrane with porous-dense-porous structure was proposed to develop a high performance membrane reactor. The triple-layer composite membrane consists of a porous Sr 0.7 Ba 0.3 Fe 0.9 Mo 0.1 O 3−δ (SBFM) layer, a dense 0.5wt% Nb 2 O 5 -doped SrCo 0.8 Fe 0.2 O 3−δ (SCFNb) layer and a porous La 0.8 Sr 0.2 MnO 3−δ –yttria stabilized zirconia (LSM/YSZ) layer. The porous layers can effectively reduce the corrosion of the reactive atmosphere to the membrane, while the dense layer permeated oxygen effectively. Compared with single layer dense SCFNb membrane reactor, the triple-layer composite membrane reactor can be operated for more than 500h. At the temperature of 900°C, the CO 2 conversion can reach 20.58% with the CH 4 conversion, CO selectivity and O 2 flux being about 84%, 97% and 2.13mL(STP)cm −2 min −1 , respectively. The porous-dense-porous structure can successfully combine the high oxygen permeation and stability of the membrane reactor.