Objective: To explore the effect of phacoemulsification combined with intraocular lens implantation in the treatment of diabetes mellitus patients with cataract, and to lay the groundwork for clinical diagnosis and treatment. Methods: Seventy patients with cataract combined with diabetes admitted from November 2017 to November 2019 were included as the research subjects. A simple random number table method was used to divide these subjects into two groups, each with 35 cases. The control group received small incision cataract extraction and intraocular lens implantation, and the observation group received phacoemulsification combined with intraocular lens implantation. The visual recovery 3 months after the operation was compared. The changes in corneal astigmatism at various time points after the operation were compared. The changes in central corneal endothelial cell density (CCD), average endothelial cell area (AVE), night reading, fine manipulation, reading and writing were compared before and after surgery. TV watching score is recorded, and complications are counted. Results: The visual acuity of the observation group at 1 month and 3 months after surgery was significantly higher than that of the control group. The difference was statistically significant (P<0.05). The corneal astigmatism of the two groups both showed a downward trend at 1 month and 3 months after surgery, the observation group being lower than the control group. The difference was statistically significant (P<0.05); after 3 months, the patient's CCD decreased, the observation group being lower than the control group, while AVE increased, the observation group being higher than the control group. The difference was statistically significant (P<0.05); 3 months after surgery, the scores of night reading, fine manipulation, reading and writing, and watching TV in the observation group were significantly higher than those in the control group. The difference was statistically significant (P<0.05). The total complication rate of the observation group was lower than that of the control group. The difference was statistically significant (P<0.05). Conclusion: Phacoemulsification combined with intraocular lens implantation can promote the recovery of vision, reduce the corneal astigmatism and the damage of corneal endothelial cells, improve the visual quality of patients, and has high safety, which is worthy of clinical application.