The influence of calcium-based catalyst/absorbent on hydrogen production of corn stalk pyrolysis-gasification was investigated in a two-stage fixed-bed biomass pyrolysis-gasification system. the results showed that addition of CaO could in-situ absorb CO2 generated from the gasification process, thus enhanced the gasification process to form more H2. As the pyrolysis/gasification temperature was 650°C, mass ratio of steam to biomass (S/B) was 2, and molar ratio of CaO to C was 1, compared with the trail without CaO addition, H2 concentration in the product gas was increased greatly from 28.7% to 56.2%, H2 yield was increased from 64.3 mL/g to 195.8mL/g, while CO2 concentration was decreased sharply from 21.5% to 1.1%. CaCO3 could be found in the used absorbent after gasification, which further proved the enhancing effect of CaO addition. Moreover, the enhancing effect of CO2 absorption of CaO was closely related to the gasification temperature. High H2 concentration and yield could be obtained with gasification temperature in the range of 600℃ to 700℃ from the pyrolysis-gasification of corn stalk. As gasification temperature higher than 700℃, the CO2 absorption capability of CaO was weakened, CaO mainly acted as a catalyst during the gasification process. The introduction of active NiO to CaO absorbent could decrease the content of small molecular hydrocarbon gases in the product gas, and increase the H2 concentration and yield. With NiO loading of 10% on CaO, H2 concentration in product gas could achieve 63.7%, while H2 yield was close to double of that with CaO addition, which reached 341.3mL/g.