The invention discloses a material circulation system of a circulating fluidized bed. The material circulation system comprises a hearth, separators, material returning legs, a collection distributor and ash amount control devices, wherein the outlet ends of the plurality of separators are separately connected to the front part of the collection separator; the rear part of the collection distributor is connected to the hearth through the plurality of material returning legs; and the ash amount control devices are arranged between the collection distributor and the material returning legs. According to the material circulation system of the circulating fluidized bed, circulation ash is collectively collected through the collection distributor; then the amount of the circulation ash falling into the hearth is controlled and adjusted through the ash amount control devices; the regional material returning amount is adjustable; the uniformity of the bed temperature in a furnace can be effectively adjusted and controlled; a good condition is provided for combustion and heat conduction; and guarantees are provided for inner-furnace high-efficient desulfuration, low Nox combustion, boiler coke forming prevention and fuel burnup improvement.