Objective To explore the effect of proprioceptive neuromuscular facilitation(PNF)on the knee abduction torque and vastus medialis-medial gastrocnemius(VM-MG)co-contraction index during walking among the old patients with medial compartment knee osteoarthritis. Methods From March to May,2022,32 old patients with medial compartment knee osteoarthritis in communities in Ji'nan were enrolled and randomly allocated to control group(n=16)and training group(n=16).The training group received PNF and the control group received home-based exercise,for six weeks.The knee abduction torque and VM-MG co-contraction index were measured using an infrared motion capture system synchronized with 3D force plate and electromyography system before and after treatment. Results Three cases in the control group and two cases in the training group dropped off.The first and the second peaks of knee abduction torque,and the VM-MG co-contraction index improved in the training group after treatment(|t|>2.460,P<0.05),and the first and the second peaks of knee abduction torque were better in the training group than in the control group(|t|>2.454,P<0.05). Conclusion PNF may optimize the load distribution between the medial and lateral compartments of the knee in patients with knee osteoarthritis.