〔Abstract〕 Objective To explore the changes in posterior tibial slope after tibial plateau fracture surgery and its relationship with knee joint function. Methods The cases of 83 patients who underwent tibial plateau fracture surgery were collected. The posterior tibial slope(PTS) of the patient's unaffected side, the affected side after surgery and the affected side at the last follow-up were measured. He knee joint score data of Lysholm, HSS and Rasmussen were evaluated and recorded, and the patients were divided into PTS<9° group and PTS≥9° group according to the PTS angle after operation. The mean of three kinds of knee joint function scores in the two groups were statistically analyzed, and the mean of PTS after operation and final follow-up was also statistically processed. The difference of PTS between the last follow-up and the healthy side was calculated, and the correlation between the difference and the knee joint function data at the last follow-up was analyzed. Results There was no significant difference in general conditions between the two groups of patients. The Lysholm, HSS, and Rasmussen score data of knee joints in PTS<9° group were significantly higher than those in the PTS ≥9° group(P<0.05). There was a significant difference in postoperative PTS between the two groups of patients compared to the last follow-up PTS(P<0.05). The difference between the last follow-up and the PTS of the unaffected side(b) was correlated with Lysholm, HSS and Rasmussen knee score data(P<0.05). Conclusion Postoperative rehabilitation exercise leads to changes in the angle of PTS. The knee joint function of patients in PTS<9° group is better than that of patients in group PTS ≥9° after surgery. The difference between the last follow-up PTS and the healthy side PTS is correlated with knee joint function. Therefore, it is necessary to try to restore the anatomical alignment of the plateau fracture during surgery or control postoperative PTS<9°.