The invention discloses a linear sieve. The linear sieve comprises a sieve box, wherein more than three horizontal sieve bodies are arranged in the sieve box in the height direction at intervals; each sieve body is provided with a corresponding secondary discharging opening; the apertures of the sieve bodies are sequentially reduced from top to bottom; two long sides of each sieve body are pressed through pressure plates I; more than three pairs of chutes with opposite openings are formed in two long side walls of the sieve box at intervals; the pressure plates I on the two long sides of each sieve body are inserted in the chutes and can slide in the chutes; a plurality of corresponding positioning holes are equidistantly formed in two long sides of each chute from head to tail; fixing holes which correspond to the positioning holes are formed in the pressure plates I on the two long sides of each sieve body; and the sieve bodies and the sieve box are fixed by each fixing hole and the corresponding positioning hole which are positioned on the same vertical straight line and through a corresponding locking piece. When the sieve bodies are required to be changed, the number of fasteners required to be detached is small, the sieve bodies can be taken out conveniently, and a sieve body changing process is simplified.