In the research of biomass chemical looping gasification technology, the production of hydrogen-rich synthesis gas has received increasing attention. In this paper, iron-nickel oxygen carriers were prepared by the mechanical and impregnation method. Chemical looping gasification experiments were performed with pine sawdust in a self-built fixed-bed reactor to prepare hydrogen-rich synthesis gas. Experimental results showed that for the iron-nickel oxygen carrier with a loading ratio of 3% NiO under reaction conditions of 800 degrees C, ratio of steam content to biomass (S/B) of 1.25, and ratio of lattice oxygen to biomass (O/B) of 0.2, the volume fraction of hydrogen in the synthesized gas reached 43.06%; correspondingly, the carbon conversion rate was 78.22%, the low calorific value of syngas was 7.49 MJ/Nm(3), and the gas production rate was 1.25 Nm(3)/kg. After modification of the iron-nickel oxygen carrier with a mass ratio of 5% K2CO3, the volume fraction of hydrogen in the prepared synthesis gas increased to 47.83%, the corresponding carbon conversion rate was 85.44%, and the low-level calorific value was 7.95 MJ/Nm(3). The gas production rate was 1.49 Nm(3)/kg.