Abstract: High concentration of H2 with a low concentration of CO and CO2 can be produced by the sorptionenhanced methane steam reforming with the CO2 sorbent addition. A mathematic model for the sorption enhanced methane steam reforming considering the activity loss of Cabased sorbents was developed and verified by the experimental data. The effect of the activity decay of three Cabased sorbents on the process of hydrogen production was explored by model　calculation. The results indicate that the breakthrough time for high concentration of hydrogen production reduces rapidly with the cycle numbers increasing for a limestone sorbent, while the breakthrough time decreases gradually for a dolomite sorbent. The effective cycle umber of CaO/Ca12Al14O33 sorbent is far more than that of dolomite and limestone.