Objective To explore the role of exercise therapy in improving motor function and relieving pain level in patients with knee osteoarthritis. Methods From September 2021 to December 2023, 66 patients with knee osteoarthritis were randomly divided into two groups by random number table method： a control group receiving routine intervention and an observation group receiving exercise therapy, with 33 patients in each group. Motor function, pain level, quality of life, and knee mobility were compared between the two groups. Results After designed intervention, the Lysholm knee scoring scale （LKSS） score in the observation group was higher than that in the control group （P<0.05）. The proportion of painless patients in the observation group was higher than that in the control group, while the proportion of moderate pain paients was lower （P<0.05）. The physical function, psychological activity, social ability, and material life state scores of Generic Quality of Life Inventory in the observation group were higher than those of the control group （P<0.05）. No significant difference was found in flexion gap between the two groups （P>0.05）, but the observation group showed larger extension gap and shorter time for active knee flexion at 90° and 120° than the control group （P<0.05）. Conclusion Exercise therapy can improve motor function, alleviate pain, and enhance quality of life of patients with knee osteoarthritis, and it is worth promoting.