The maximum sewing speed of such machinery reaches 6500 R.P.M. The sewing performance is stable, the light movement, low noise, small vibration and the rotation is stable and smooth. The adoption of the incline needle bar needle-bar mechanism, needle bar thread-taking-up, looper thread-hooking, differential feeding can form the three-thread, four-thread, five-thread overlock stitches. They are major equipments for edge folding and overlocking. The low-tension thread-passing device features the convenient regulation. The stitches are smooth and beautiful. The ingenious machine body and the wide worktable are applicable for the sewing of trousers, pajamas, T-shirts, shirts, sports wear and all kinds of knitting materials. As required by users, three-thread, four-thread and five-thread machine types are available.