The so-called M lip is a lip with a fuller lip bead in the middle, a dome on both sides, and an upward effect on the corner part of the mouth, showing the overall shape of the letter M. It is a more characteristic and linear effect, which is in line with the shape of oriental aesthetics. At present, there are various surgical procedures for M-lipoplasty. For thin lips, it is necessary to thicken the lip bead area with fillers. For thick lips, it requires partial removal and thinning on both sides of the thick area, thus achieving an immediate M-lipoplasty effect. But M lip surgery also has certain risks, as follows: 1, M lip surgery area incision healing poorly, bleeding, bruising hematoma, etc., may also cause proliferative scars, the need for late scar removal treatment; 2, M lip surgery after both sides of the asymmetry, short-term asymmetry with no complete swelling, scar softening, etc., but if the complete recovery is still asymmetric, further surgical repair is required; 3. M lip surgery, for thick lips of the recipient, M lip surgery after thinning, the curve of their lips become flat, the appearance of lip shape is not obvious or thinning parts of the thickening, etc., thus weakening the final effect, need to repair again; 4, M lip surgery after the appearance of red lips, dry mucosa, less mucus secretion, etc., and surgery damage mucus glands related, need about six months to gradually recover.