Oxygen carriers with the ability to achieve complete fuel conversion and high H2 production capacity are always desired in the chemical looping H2 generation (CLHG) process. In the present work, we decorated the Fe2O3-Al2O3 with little co-dopant of CuO and NiO, then evaluated its performance in the biomass syngas fueled CLHG process, and characterized it by XRD, SEM, XPS, H2/CH4-TPR and H2O-TPO analysis to explore its reaction mechanism. Results show that the Fe2O3-Al2O3 with co-introduction of CuO and NiO (4.76 wt.%) behaved much better in the CLHG process than the Fe2O3-Al2O3 and Fe2O3-Al2O3 with any single addition of CuO and NiO, the conversion of fuel (especially the CH4 in it), H2 yield and H2 energy efficiency were significantly promoted, and obtained the maximum value of >99%, 6.35 mmol/g Fe2O3, 77.9%, respectively. A strong interaction between Fe2O3, CuO and NiO and the ferrite spinel phase formed during the OC preparation were observed by XPS and XRD analysis. Besides, H2/CH4-TPR and H2O-TPO analysis show the enhanced redox reactivity of Fe2O3-Al2O3 with the co-addition of CuO and NiO. Furthermore, the time-resolved OC conversion and phase evolution in the OC reduction process, together with the DFT calculation, demonstrate the synergistic effect of CuO and NiO, the formation of FeNi and Cu in the early stage of OC reduction facilitates the lattice oxygen release, thus promoting the fuel conversion and deep reduction of OC.