The invention relates to a gasification process which uses O2+CO2 or air+CO2 as a gasifying agent for fluidized bed CO gasification furnace, and its device, using O2 and CO2 as gasifying agent, and 0-10 mm-sized fine coke and blind coal as raw materials, adopting continuously-gasifying fluidized bed gasification furnace as a gasifier, namely adopting continuous gasification process; or using air and CO2 as gasifying agent, using 0-10 mm-sizd fine coke, blind coal, lean coal, long flame coal and wood coal as raw materials, adopting intermittently-gasifying fluidized bed gasification furnace as a gasifying device, namely adopting intermittent gasification process, reducing CO2 gas into CO gas to make highly pure CO gas as organic synthetic raw material. The advantage are the raw material source is rich, it retrieves and uses the CO2 gas to act as the gasifying agent.