In this paper, numerous effects of immunosuppressive regimen of mycophenolate mofetil (MMF) on CNI-related renal damage after lung transplantation are evaluated thoroughly. For this purpose, 110 lung transplant recipients who were treated in our hospital from March 2016 to January 2018 were randomly selected. All patients took prednisone acetate tablets or rapamycin at the same time or not at the same time. MMF is 1 g every time, twice a day, and adjusted according to the re-examination. According to the different drugs taken by 110 patients, they were divided into cyclosporine A group and tacrolimus group. Among them, 92 patients in cyclosporine A group took cyclosporine A; 18 patients in tacrolimus group took tacrolimus. The clinical data of age and gender of the two groups were collected, To observe and compare the occurrence of CNI-related renal damage in lung transplant recipients and different immunosuppressants. The CNI dosage of tacrolimus group and cyclosporine A group was compared before and after MMF. The changes of serum creatinine level and serum creatinine clearance rate were measured before MMF administration and 30, 60, and 90 days after MMF administration, to observe the complications of CNI-related renal damage after lung transplantation. Experimental results showed that there were 16 cases (14.55%) of CNI-related renal damage in lung transplant recipients and different immunosuppressants, including 10 cases (11.36%) in males, 6 cases (27.27%) in females, 11 cases (12.09%) in tacrolimus group, and 5 cases (26.32%) in cyclosporine A group. There was no significant difference between the two groups ( > 0.05). Compared with MMF before and after administration, CNI dosage of cyclosporine A group and tacrolimus group decreased significantly ( < 0.01). Compared with MMF before administration, serum creatinine level decreased and serum creatinine clearance rate increased significantly ( < 0.05). In the follow-up, 16 patients with CNI-related renal damage were found to be immune rejection before the adjustment of immunosuppression program, no complications such as immune rejection, myelosuppression, and infection occurred within 15 months after the adjustment of immunosuppression program, blood glucose increased in 3 patients within 2 years after operation, blood lipid increased in 1 patient, urea increased in 1 patient, and uric acid increased in 1 patient. MMF immunosuppressive therapy based on CNI reduction is a safe and effective immunosuppressive therapy, which can significantly reduce immune rejection, improve renal function, and play an important role in improving CNI-related renal damage after lung transplantation.