The invention discloses a flue structure and belongs to the field of steel structures. The flue structure is characterized in that four flue walls are formed by connecting multiple support panels; a plurality of steel frame strips are fixed on the outer wall face of each flue wall along a smoke flowing direction at intervals of a first preset distance; the steel frame strips on the adjacent outerwall faces are connected; a plurality of slats are fixed between the adjacent two steel frame strips along the smoke flowing direction at intervals of a second preset distance; a plurality of second slats are fixed in a direction perpendicular to the smoke flowing direction at intervals of a third preset distance; a plurality of inner support rods are arranged in the flue structure; a steel framestrip is fixed correspondingly to each outer wall face at the end butting position of each inner support rod. As the first slats and the second slats replace part of the steel frame strips, fewer steel frame strips and fewer corresponding inner support rods can be used, operation and maintenance costs are reduced, and smoke flowing resistance is decreased.