Objective To analyze the effect of two kinds of keratotomy on corneal endothelial injury after phacoemulsification and explore the related factors. Methods 109 patients who received phacoemulsification in Chengdu Third People's Hospital from October 2022 to October 2023 were divided into the control group (n=52, phacoemulsification needle inclining upward) and the study group (n=57, phacoemulsification needle inclining downward) by adopting different types of nucleus chopping. Postoperative corneal endothelial cell injury rate and corneal endothelial cell related indexes were compared. According to the corneal endothelial injury after phacoemulsification, the patients were divided into injury group (n=29) and non-injury group (n=80).The influencing factors of corneal endothelial injury after phacoemulsification were analyzed by single factor and Logistic multivariate analyses. ResultsCorneal endothelial cell damage rate of study group was lower than that of control group (P<0.05). At 2 weeks after surgery, endothelial cell density was risen while area of corneal endothelial cell, coefficient of variation, proportion of hexagonal cell and corneal thickness were declined in study group (P<0.05). There were no significant differences in sex, hypertension, diabetes mellitus, axial length of eye, injection time, preoperative naked visual acuity and best corrected visual acuity between the injured group and the uninjured group (P>0.05), but there were significant differences in age, lens nucleus hardness, shallow anterior chamber, ultrasonic energy, phacoemulsification time and cumulative energy released between groups (P<0.05). Logistic regression analysis showed that age, lens nucleus hardness, shallow anterior chamber, ultrasonic energy, phacoemulsification time and cumulative release energy were independent risk factors leading to corneal endothelial injury (P<0.05). Conclusion Compared with phacoemulsification needle inclining upward, phacoemulsification needle inclining downward can reduce corneal endothelial cell injury and improve corneal endothelial related indexes. Corneal endothelial cell injury after phacoemulsification is affected by age, lens nucleus hardness, shallow anterior chamber, high ultrasonic energy, phacoemulsification time, cumulative release energy