The present invention discloses a chemical looping combustion power generation process and system using landfill gas, which falls into the range of efficient landfill gas cleaning and utilization technique. This power generation system is composed of a landfill gas collection system, a chemical looping combustion system, and a gas and steam combined cycle power generation system. In the process, the simple substance metal in the air reactor takes oxidation reaction with air, the landfill gas and the obtained metal oxide take reduction reaction in the fuel reactor to generate single substance metal, CO2 and water vapor, and the reduced simple substance metal returns to the air reactor via the refeed line and completes the regeneration of metal oxide; the gas at the outlet of the fuel reactor and the gas at the outlet of the air reactor are led to two separate gas and steam combined cycle power generation systems for power generation and CO2 recovery.