The invention discloses a circulating fluidized bed oxygen-deficient combustion catalytic oxidation staged combustion boiler system and method. An outlet of a circulating fluidized bed oxygen-deficient combustion hearth is connected with a cyclone separator, and the cyclone separator communicates with the circulating fluidized bed oxygen-deficient combustion hearth through a material returning pipe, a material returning system and a circulating material returning port to form a circulation loop; and a flue gas outlet of the cyclone separator communicates with a tail vertical flue arranged downwards, and a secondary combustion chamber, an air supplementing chamber and a CO catalytic oxidation device are sequentially arranged in the tail vertical flue from top to bottom. According to the circulating fluidized bed oxygen-deficient combustion catalytic oxidation staged combustion boiler system and method, overall excess air coefficients are low, heat loss of flue gas exhaust can be reduced, and heat efficiency of the boiler can be improved.