Objective To investigate biomechanical properties of double eyelid surgery and its clinical application in upper blepharoplasty .Methods In the mild ptosis correction combined with double eyelid surgery ,the main force from levator was assigned to upper tarsus to open eyes .At the same time ,not only it could ensure the enough height of palpebral fissure ,but also had relatively sta-ble and persistent double eyelid .For those who had sunken upper eyelid ,were given fat transposition and/or autologous fat grafting .For those who had medial epicanthal fold ,to achieve a pleasing eye ap-pearance ,we performed epicanthoplasty .Results After 6 months to 2 years of follow-up ,15 cases had unsatisfactory results and underwent secondary surgery .The revision reason was as follows :7 pa-tients had asymmetry double eyelid width ,3 patients had insufficient correction for ptosis ,2 patients had shallower and narrower double eyelid line .In 3 cases ,the correction of the upper sunken was in-sufficient .The remaining 164 patients with mild ptosis were well corrected ,and the double eyelid was stable and natural ,and the results were satisfactory .There were no major complications .Conclusions During mild blepharoptosis correction combined with double eyelid surgery ,reasonable treatment of the biomechanical balance has certain clinical significance for avoiding postoperative complications and improving the effect of double eyelid surgery .