The utility model discloses a circulating fluidized bed boiler. The device comprises a rectangular box body, an air outlet is formed in the center of the right side surface of the rectangular box body; an air outlet pipe is arranged at the air outlet; a micro fan is arranged in the air outlet; the left side of the gas outlet is fixedly connected with a micro gas-solid separator; strip-shaped grooves are formed in the upper edges of the two side surfaces of the rectangular box body; a plurality of strip-shaped grooves are formed in the rectangular box body, supporting rods are embedded in the strip-shaped grooves, the supporting rods are jointly and fixedly connected with a heating pot, circular grooves are machined in the lower edges of the two side faces of the rectangular box body, a rectangular shell is embedded in each circular groove, and a combustion furnace is jointly embedded in each rectangular shell. The utility model has the beneficial effects that the heat loss is low, theheat efficiency is high, solid fuel particle impurities are separated by the micro gas-solid separator and then re-combusted, the cycle performance is good, the energy is saved, the efficient utilization of fuel is realized, the combustion is high, the moving effect is good, and the movement is convenient.