Objective: To explore the effect of continuous passive motion training (CPM) on the lower extremity motor function and inflammatory factors in the elderly after total knee arthroplasty(TKA). Methods: 82 elderly patients with TKA were randomly divided into control group (41 cases) and observation group (41 cases). The control group was treated with routine rehabilitation measures, and the observation group was treated with CPM on the basis of the control group.The swelling degree and the score of knee joint function (HSS) were recorded on the 1d before training, 1d, 3d, 7d and 14d after training. The serum levels of IL-6, IL-1茁 and TNF-琢 were measured by enzyme-linked immunosorbent assay (ELISA) before and after training. After 100 d follow-up, adverse reactions of the two groups were recorded, and Kaplan-Meier method was used to evaluate the first independent activity of the patients. Results: On the 1d after training, the swelling degree of the patients in the observation group was significantly lower than that in the control group (P<0.05), but there was no significant difference in HSS function score between the two groups (P>0.05); on the 7d and 14d after training, the swelling degree of the patients in the observation group was significantly lower than that in the control group (P<0.05), while the HSS function score was significantly higher than that in the control group (P<0.05). The expression levels of IL-6, IL-1茁 and TNF-琢 on the 3d, 7d and 14d after training in the observation group were lower than those in the control group (P<0.05). The incidence of complications in the observation group was significantly lower than that in the control group (P<0.05). Kaplan-Meier analysis showed that the average time of the first independent activity in the observation group was 69d, shorter than 82.5d in the control group, the difference was statistically significant (P<0.05). Conclusion: CPM has obvious advantages in improving the degree of swelling and knee joint function of the elderly patients, and helps to reduce the occurrence of complications, and its mechanism may be related to reducing the inflammatory response of the patients. [ABSTRACT FROM AUTHOR]