The reaction kinetics of the oxidative coupling of methane (OCM) was studied in a 1% Sr/La2O3 -Bi2O3 -Ag -YSZ cataytic membrane reactor with oxygen pumping type. The reaction network for the OCM reaction was defined. The reaction mechanism was developed and the rate equations were determined. The results showed that the OCM reaction over the catalytic membrane with oxygen pumping type followed a Rideal - Redox mechanism. The technique of solid -electrolyte - potentiometry (SEP) was used to investigate the effect of internal diffusion.