The invention discloses an air-drying device for preliminary processing of hemp and cotton, which comprises a shell; a net tube is installed inside the shell, and a gap is arranged on the net tube along its axis, and an inner wall of the net tube is installed in the gap along the inner wall of the net tube. Corresponding net cover, the net cover is fixedly connected with the cylinder, and the net cover is fixedly connected with the bearing through the strut, the bearing is connected with the rotating shaft with interference, the top of the shell is provided with a material inlet, and the inner wall of the shell is uniform An electric heating fan is installed, the casing is fixedly connected to the base, the first motor and the second motor are fixedly installed on the base, a controller is installed on the outer wall of the casing, and a discharge port is arranged on the side of the casing near the conveyor belt , a collection box is arranged behind the outlet. The invention air-dries the cotton and linen through the electric heating fan, and at the same time uses the first motor to drive the rotation of the net cylinder, so that the cotton and linen in the net cylinder are heated evenly, so that the air-drying effect is better.