This application relates to a folding and sewing method, a folding device, and a bag-attaching
machine. The folding and sewing method uses a folding device to sew a fabric bag and includes the following steps: a tongue-pressing plate is placed on the worktable; a tongue-pressing plate driver drives the tongue-pressing plate to extend outward and places the bag on the tongue-pressing plate; a bracket driver drives a mounting bracket to move towards the tongue-pressing plate; when the tongue-pressing plate contacts an elastic body, the mounting bracket stops moving; a
magnet driver drives a magnetic suction component to move towards the tongue-pressing plate; when the magnetic suction component passes through a perforated hole and is magnetically attracted to the bag and the tongue-pressing plate, the
magnet driver drives the tongue-pressing plate to press against the elastic body, causing the tongue-pressing plate to be recessed into the elastic body. The folding and sewing method, folding device, and bag-attaching
machine provided by this application solve the problem of high manufacturing costs caused by the need to frequently change the concave mold when changing bag styles.