As “carbon neutrality” becomes one of the most critical topics in the world, interest in capturing carbon dioxide from industrial processes is growing. In this study, we proposed an efficient process for recycling biomass resources. Firstly, a bifunctional Ni/CaO catalyst based on Ce modification was developed by conducting corncob steam gasification experiments at 600 °C in a tube furnace. At Ce doping of 0.75 and Steam/Carbon = 7, the H2 concentration reached 87.65 ± 1.46 vol% and the H2 yield reached 40.04 ± 0.74 mmol/gbiomass. The cycle test verified that Ce0.75-Ni1/Ca7 had good cycle stability. Secondly, we designed multi-stage variable temperature steam gasification experiments. The experimental results showed that the CO yield in the second stage was 15 times higher than before the introduction of gasification carbon, and the total syngas yield was increased by 2.32 times. Furthermore, the H2/CO molar ratio could be controlled by modifying the addition of gasification carbon, which was advantageous for downstream product synthesis. Implement the synergistic capture and conversion of CO2 in an integrated process, while simultaneously producing high-value synthesis gas, fully utilizing the biomass.