The invention provides a chained reactor for a biomass-coal divisional fluidized bed. Because the production of biomass is seasonal, the biomass cannot be stably supplied, as commonly used energy, coal reserves is gradually reduced, and the mixed combustion cannot achieve sufficient utilization to fuels. The chained reactor provided by the invention comprises a biomass reaction chamber (1), an auxiliary reaction chamber (2) and a coal reaction chamber (3), wherein the auxiliary reaction chamber is divided into a separation chamber (5) and a preheating chamber (6) through a middle separation wall (4), a wind catcher (7) is arranged at the bottom of the preheating chamber, the wind catcher is connected with a draught fan (8), a gas exhaust tube (9) is mounted in the middle of the separation room, the bottom end of the gas exhaust tube is connected with the middle separation wall, oblique plates (10) are respectively connected to both sides of the upper end of the gas exhaust tube, and gas exhaust ports (11) are respectively formed in the position below the connected parts of the oblique plates and the gas exhaust tube. The chained reactor provided by the invention is used for the chained reaction of the biomass-coal divisional fluidized bed.