The computerized step-by-step side cutter can adjust the stitch size step by step; nine patterns of stitches are adjustable, and the large cutting opening makes the cutting smoother. The machine is equipped with an adjustable side cutter mechanism, which is easy to adjust and can sew and tailor the material at one time. It adopts connecting rod feeding mechanism and connecting rod thread take-up, rotary hook thread hooking, upper and lower shafts rotate with spiral bevel gears, and fully automatic lubrication.