Ultrasound is commonly used to treat knee osteoarthritis (KOA), which has unique advantages with regard to relieving pain and inflammation as well as delaying cartilage degeneration, but the underlying mechanisms are less clear. The study aimed to investigate the therapeutic effects of ultrasound on vascular endothelial growth factor (VEGF) expression in cartilage, the synovium, and synovial fluid (SF) in a rabbit model of KOA. Twenty-four New Zealand rabbits were randomly divided into ultrasound (group A), sham ultrasound (group B) and no-ACLT control groups (group C). Six weeks after undergoing anterior cruciate ligament transection (ACLT), group A was treated with ultrasound and group B was treated with sham ultrasound. Two weeks thereafter, the morphology of the synovium and cartilage were observed. Cartilage and synovium were scored using the Mankin scale and Krenn V scores, respectively. VEGF expression in the cartilage, SF, and synovium of ACLT knee joints was analyzed via immunohistochemistry, western blotting, and RT-PCR. Cartilage degeneration and synovitis were the most severe in group B and the least severe in group C. Similarly, Mankin scores and Krenn V scores were highest in group B and lowest in group C (p<0.05). There were also significant differences in the VEGF IOD of cartilage or synovium, VEGF protein content in SF, and VEGF mRNA expression in cartilage or SF (p<0.05). Ultrasound can relieve synovitis and delay cartilage degradation, and the mechanisms of ultrasound for the treatment of KOA may involve inhibition of the expression of VEGF in the synovium, SF, and cartilage.