It is of great significance to develop a new method for hydrogen production and syngas production that utilizes oxygen carrier catalysts to directly decompose water to produce pure hydrogen in one stepand  couple it with biomass thermal conversion. Iron-based oxygen carriers doped with Ce-Ni were prepared by metal chelating sol-gel method. Pure hydrogen and hydrogen-rich synthesis gas were prepared by chemical looping water decomposition coupled with acetic acid thermal decomposition. Firstly, under the action of oxidized oxygen carriers, acetic acid catalyzed thermal decomposition to produce hydrogen-rich syngas. And the oxygen carrier was reduced to realize the migration of lattice oxygen in the oxygen carrier, and the thermal decomposition process was strengthened by in-situ CO2 adsorption. Secondly,hydrogen production was achieved through the iron steam process using the reduced oxygen carrier with water. It is found that the in-situ CO2 adsorption is enhanced during the catalytic thermal decomposition of acetic acid, which can improve the purity of H2 in syngas and reduce carbon deposition. Compared with undoped pure iron oxide and blank quartz samples, the Fe-based oxygen carrier doped with appropriate amount of Ce and Ni has obvious hydrogen production effect. With the increase of Ce and Ni, the amount of CO2 and CO produced in the acetic acid decomposition stage decrease, while H2 increases firstly and then decreases during water decomposition. The optimum molar ratio of oxygen carrier Fe, Ce and Ni is 100∶10∶3.The addition of CO2 adsorbent with different mass ratio of oxygen carrier can effectively reduce the amount of CO2 and CO in syngas, and the best mass ratio is 1∶2.Under this condition, the syngas composition of H2 is increased by 11.96%-26.17%, CO2 is reduced by 22.85%-49.28%, CO is reduced by 29.18%-34.05%, and the oxygen carriers remain good stability after 15 cycles.