The water gas shift reaction in a catalytic bubbling fluidized bed reactor was investigated by using simulated syngas (40% H2, 40% CO and 20% CO2) for the pre-combustion CO2 capture and hydrogen production application. A commercial low temperature shift (LTS) catalyst with particle sizes of 200-300 μm was used to investigate the promotion effect by exchanging the fixed bed reaction with the fluidized bed reactor. The effects of the reactor temperature (180-400 ℃), space velocity (800-4,800 cm3/hㆍg), and steam/CO ratio (1.0-2.5) on the CO conversion and syngas composition were determined, and the highest CO conversion was 86.8% at 300 ℃ with the LTS catalyst at a space velocity of 800 cm3/hㆍg and steam/CO ratio of 2.5. The experiments exhibited an improvement in activity and a conversion reached that given by equilibrium at temperatures over 300 ℃. Also, the performance was much improved than that when a fixed bed system was used.