The invention relates to a flue automatic dust removal device, and effectively solves the problem of low utilization rate of filter screens of a conventional flue dust removal device. The technical scheme to be solved by the invention includes that the flue automatic dust removal device includes a cylinder, a plurality of sliding grooves are formed in the cylinder, the bottom surface of each sliding groove has lower left and higher right, and an annular groove is formed at the right ends of the sliding groove; the center of the cylinder is provided with a core shaft; the core shaft is providedwith a first sleeve; the first sleeve is provided with support rods, each support rod is provided with a reset press spring, and the left side of each support rod is provided with a filter screen; the core shaft is provided with a first press spring; the left end of the core shaft is provided with a circular disc, the circular disc is provided with an elastic block, the outer side of the circulardisc is provided with a second sleeve, the second sleeve is provided with a groove, and the outer circular face of the second sleeve is provided with a dust scraping plate which can do reciprocatingmotion; the cylinder is internally provided with a fan-shaped through groove, and two groove walls in the front direction and the rear direction of the fan-shaped through groove are each provided witha separation plate; the lower sides of the two separation plates are provided with an arc-shaped plate with an upwards arc-shaped surface, the arc-shaped plate is in rotating connection with the first sleeve, and the two separation plates, the arc-shaped plate and the inner wall of the cylinder form a fan-shaped channel. The flue automatic dust removal device is ingenious in conception and intricate in structure.