Objective:To investigate the relationship between Ki-67 and PD-L1 in patients with non-small cell lung cancer (NSCLC) and their effects on prognosis. Methods: A total of 401patients, who were pathologically diagnosed as NSCLC in Changhai Hospital from January 2012 toAugust 2018, were enrolled as study subjects; and the patients were immunohistochemically tested for PD-L1 and Ki-67. The clinical and pathological data were collected, and the follow-up was performed regularly. The correlation between Ki-67 and PD-L1 and their effects on postoperative DFS and post-chemotherapy PFS were statistically analyzed. Results: Positive rates of PD-L1 and Ki-67 in NSCLC tissues were 37.9% (152/401) and 96.3% (386/401), respectively. Univariate analysis showed that Ki-67 was an influencing factor for PD-L1 expression (OR=0.33, 95%CI=0.28-0.39, P<0.0001); Curve Fitting analysis showed a positive correlation between Ki-67 and PD-L1; threshold effect analysis, segmentation multivariate logistic and ROC curve analysis showed 14% is a relatively suitable threshold for Ki-67 to be combined with PD-L1. Kaplan-Meier analysis showed that patients in Ki-67 high expression group had a significantly shorter post-operative DFS than those in Ki-67 low expression group ([21.88±11.25] vs [41.22±16.25]m, P< 0.0001), patients in PD-L1 positive group had a significantly shorter DFS than those in PD-L1 negative group ([24.75±14.59] vs [38.27± 16.75]m, P<0.0001)], and patients in Ki-67 high/PD-L1 positive group had the shortest DFS as compared to the other three groups ([20.57±11.33] vs [24.11±10.79], [36.00±16.79], [42.91±15.77]m, P<0.0001).As for post-chemotherapy PFS, patients in Ki-67 high expression group was significantly longer than those in Ki-67 low expression group [(7.70±3.01) vs (5.80±2.99)m, P=0.016), but there was no significant difference between PD-L1 positive group and PD-L1 negative group [(7.04±3.21) vs (6.33±3.06)m, P=0.22); for combined evaluation with Ki-67 and PD-L1, the PFS of two Ki-67 high expression groups was significantly longer than the other two Ki-67 low expression groups [(7.74±3.25) vs (7.43±2.38) vs (4.91±1.97) vs (6.02±3.19)m, P=0.041). Conclusion: Ki-67 is positively correlated with PD-L1 in NSCLC patients, and Ki-67 14% is a suitable threshold for combined use with PD-L1. Both Ki-67 and PD-L1 are predictors of poor prognosis. The combination of the two has an "additive effect" on the prediction of poor prognosis, and patients with high Ki-67 expression are more sensitive to chemotherapy.