To study the application of island sternocleidomastoid myocutaneous flap in repairing the buccal composite tissue defect especially penetrated tissue defect. The flap pedicle included upper part OF sternocleidomastoid muscle and occipital artery. The rotation point was located at 2 cm below the mastoid. The distance between the pivot point and distal border of the defect was the length of the muscular flap. The width of the flap was slightly larger than the defect, but should not be more than 7 cm. The lower border of the flap should not exceed 2 cm below the collar bone. The flap was elevated from the starting point of the sternocleidomastoid muscle and beneath it. The pedicle only contained muscle. The flap was transferred to the defect through the tunnel between the pedicle and defect. The wounds at donor sites were closed directly or with skin graft or local flaps. 12 cases were treated, including 10 cases of buccal soft tissue tumors and 2 cases of buccal penetrated defects. All the musculocutaneous flaps survived with good texture, color and thickness. The island sternocleidomastoid myocutaneous flap is an ideal flap for large buccal composite tissue defect with reliable blood supply. It is easily performed and very practical.