The invention discloses a flue device for thermal power generation and belongs to the field of steel structures. The flue device is characterized in that multiple support surface plates are connectedto form four flue walls of the flue device, a plurality of steel frame bars are arranged on the outer wall face of each flue wall along the flowing direction of flue gas at first preset intervals, thesteel frame bars of every two adjacent outer wall faces are connected, a plurality of steel beams are fixedly arranged between every two adjacent steel frame bars along a direction vertical to the flowing direction of the flue gas at second preset intervals, and a plurality of rib plates are fixedly arranged between every two adjacent steel beams along the flowing direction of the flue gas at third preset intervals. The flue device has the advantages that by using the steel beams and the rib plates to replace part of the steel frame bars, the use number of the steel frame bars and corresponding inner support rods can be reduced, flue gas flowing resistance is reduced, internal area, which needs corrosion preventing, of the flue device is reduced, and operation and maintenance costs are reduced.