Chemical looping gasification (CLG) in a dual fluidized bed gasifier was proposed to increase the H2/CO ratio and to simplify the process in gasification. The gasifier offered two separate fluidized bed reactors, fuel reactor (FR) and steam reactor (SR), for biomass gasification and H2 production. Iron ore was used as the oxygen carrier (OC), providing lattice oxygen for gasification in the FR, transferring to the SR for reacting with steam to produce H2, and then achieving the circulation and reoxidation through the loop seal. The product gas from the FR and the SR could be controlled to make high H2/CO ratio syngas by this process. The experiment for the CLG of sawdust was conducted in a dual fluidized bed gasifier, regarding the influence of different FR temperatures, SR temperatures, steam/biomass (S/B) ratios, and steam preheating temperatures. The optimum operating condition was obtained by the analysis showed as follows: the FR temperature of 820 degrees C, the SR temperature of 910 degrees C, the S/B ratio of 1.50 kg kg(-1), and the steam preheating temperature of 500 degrees C. At this condition, the cold gas efficiency in the FR was 77.21% and the H2 yield in the SR was 0.279 Nm3 kg(-1). Overall, the CLG process of sawdust carried out in the present work suggests that a high H2/CO ratio syngas production was simple and promising.