Cataract is the first ophthalmological blinding eye disease. In recent years, phacoemulsification has become the preferred method for the treatment of cataract due to its short time and small damage, which is widely used by ophthalmologists. With the continuous improvement of technology, serious complications caused by phacoemulsification become less and less. But the phenomenon of postoperative corneal edema is not uncommon. The incidence of corneal edema is especially high in patients with diabetic cataracts. This paper reviewes the concept of corneal edema, pathogenesis and the related factors of corneal edema after phacoemulsification in diabetic cataract patients.