The invention provides a secondary utilization method for hot air of a fluidized bed furnace. The method is implemented by a device comprising a kiln head cover, a dryer, the fluidized bed furnace, akiln tail cover, an air bellow, an air blower, an ash discharge hopper, a cyclone dust collector, a duplex temperature-resistant relay valve, a dust settling system, a dust settling chamber, an induced draft fan, an alkaline water desulfurizer, a chimney, a wet ash pool and a forklift ash discharge path. The method is characterized in that the dryer is mounted in the fluidized bed furnace, and anair outlet pipe is arranged at the upper end; the kiln head cover and the kiln tail cover are mounted at the two ends of a rotating body, and a kiln head cover air outlet pipe is connected with the cyclone dust collector and then is connected with the dust settling system; a kiln tail cover air inlet pipe is connected with a fluidized bed furnace air outlet pipe; hot air is discharged from the kiln head cover air outlet pipe, enters the cyclone dust collector and then enters the dust settling system; a dust settling chamber air outlet pipe is connected with an induced draft fan air inlet pipe,and the induced draft fan is connected with an alkaline water desulfurizer air inlet pipe and then connected with the chimney; dust sludge is discharged into the wet ash pool; the air bellow is arranged at the bottom of the fluidized bed furnace, and the air blower supplies oxygen for burning; dust ash of the cyclone dust collector is discharged into the wet ash pool and loaded by a forklift foroutward transportation, and the overall process adopts closed loop and no wastewater is discharged outside.