Objective To observe the effect of intra-articular injection of platelet-rich plasma (PRP) and Sodium Hyaluronate (SH) on knee osteoarthritis by musculoskeletal ultrasound. Methods Ninety-two patients with KOA were divided into study group and control group randomly. PRP and SH were injected into the knee joint cavity respectively. Before and after treatment, the Numerical Rating Scale（NRS）、The Western Ontario and MeMaster Universities Osteoarthritis Index (WOMAC)were recorded.The synovial thickness, joint effusion, and blood flow signal in the synovium were measured by ultrasonography.The levels of tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) in knee joint fluid were detected by ELISA . Results After treatment, NRS, WOMAC, the synovial thickness, joint effusion, and blood flow signal in the synovium, the level of TNF-α and IL-6 were significantly alleviated in the two groups, and the study group was more significantly alleviated than the control group.Conclusion Intra-articular injection of PRP is more effective than SH in the treatment of KOA, which can effectively relieve joint effusion, synovial edema and other inflammatory manifestations, and reduce the levels of TNF-α and IL-6 in synovial fluid. Musculoskeletal ultrasound has great value in the diagnosis and therapeutic evaluation of KOA.