Preoperative design is the key to the success of double eyelid surgery. Double eyelid surgery's preoperative design should follow the principle of harmony, unity and bilateral symmetry, and design a specific and coordinated double eyelid shape according to the age, personality, occupation, face shape, eye shape and individual situation of facial organs of the beauty seeker. There are many forms and classification methods of double eyelids, but there are three recognized classifications, namely, parallel type, wide tail type and crescent type.

A. Parallel type: refers to the double eyelid folds parallel to the upper eyelid margin, which is especially suitable for people with thin and short eyelids;

B. Wide tail type: refers to the double eyelid fold with narrow inside and wide outside, which is suitable for most patients with single eyelid;

C crescent shape: it means that the folds of double eyelids are wider in the middle, which is rarely used in double eyelid surgery. The width of double eyelids, that is, the distance from the double eyelid line to the upper eyelid edge, can be divided into three types: wide, medium and narrow.

A. Wide double eyelids: refers to the width exceeding 8 mm This design is suitable for people with rectangular faces and strong personalities, as well as a few dancers and comedians.

B. Moderate double eyelids: refers to the width of 6-8 mm, which is suitable for most patients.

C. Narrow double eyelids: refers to the width below 5 mm. This design is suitable for people who have small eyes and don't want to be noticed as double eyelid surgery.

In the actual design, the length of palpebral fissure, the distance between eyebrows and eyes and the function of levator palpebralis muscle will be considered comprehensively.