Double eyelid refers to a shallow furrow of skin on the upper eyelid above the lid margin. When the eyes are opened, the skin below this furrow moves up, while the skin above this furrow is loose and hangs downward at the heavy eyelid furrow, making the eyes look bigger and more luminous. There are five main types of double eyelids, namely, open fan double eyelids, flat fan double eyelids, parallel double eyelids, European type double eyelids, and crescent type double eyelids, and their characteristics and suitable people are as follows: 1. Open fan double eyelids: open fan double eyelids are one of the classic double eyelids, which are characterized by narrow inner and wide outer, with natural post-operative effects, suitable for people with more upper eyelid fat, more natural and classical, with oriental mood. However, people with deep eyelid folds are not recommended to choose open fan type double eyelids, and it is recommended to perform with open inner eye angle surgery for better results; 2. flat fan type double eyelids: the shape of flat fan type double eyelids is a kind of middle between open fan type and parallel type, which looks similar to open fan type from a distance, if the double eyelid line is wider, it will show the shape of parallel type double eyelids. The flat fan type double eyelid is natural and not exaggerated, it looks very dignified, suitable for candidates with no inner canthus, long eyes, thin and tight eyelids; 3, parallel double eyelid: parallel double eyelid is a double eyelid line and the upper lid edge is basically parallel, the width inside and outside is basically the same, this kind of eye is dignified and atmospheric, common in the West, making the five features more obvious, suitable for the high arch of the eyebrows, eyebrows are far from the eyes and the upper eyelid is thin 4, European type double eyelids: European type double eyelids and parallel type is basically the same, can be understood as a three-dimensional version of the parallel type, suitable for deep contour, high brow bone, three-dimensional features of the crowd, but small eyes, upper eyelid fat is not suitable for people; 5, crescent double eyelids: crescent double eyelids will look very playful and cute, suitable for people with round eyes, ageing effect is very obvious. It is recommended that candidates go to a professional medical institution, choose an experienced doctor and customize the right double eyelid shape according to their own characteristics.