The invention discloses a displacement chamber used for an atmosphere roller kiln. The displacement chamber includes a furnace body with a gas displacement cavity and a plurality of conveying rollersinstalled on the furnace body in the direction of material conveying at intervals. The two ends of the gas displacement cavity are provided with material inlet and outlet openings correspondingly. A gate device used for opening and closing the material inlet and outlet openings is arranged at the position, corresponding to the material inlet and outlet openings, of the furnace body. The gate device includes a valve plate and a lifting driving assembly. The valve plate is installed at the lifting driving end of the lifting driving assembly through a swinging mechanism and swings to the positionto form spacing with the material inlet and outlet openings in the direction of material conveying under a self weight function. The furnace body is provided with more than one gate closing pushing part which forces the valve plate to swing for being attached to and seal the material inlet and outlet openings when the lifting driving assembly drives the valve plate to move downwards and is separated from the valve plate when the lifting driving part drives the valve plate to move upwards. The displacement chamber has the advantages of being simple in structure, small in occupancy space, low in cost, easy to operate and control, good in sealing effect and conducive to improve the product quality.