objective To evaluate the curative effect of acupotomy on knee osteoarthritis by high frequency ultrasound, and its clinical value. Methods Selected 40 cases of knee osteoarthritis who were treated with acupotomy in our hospital during February 2017- April 2018. Before and after the treatment, observed the structural changes of the knee by high frequency ultrasound, and the synovial thickness and the range of joint effusion were measured and recorded for comparative analysis. Results The score of visual analogue scale (VAS) after treatment was significantly lower than that before treatment, the differences was statistically significant (P<0.05)；The circumferential diameter of the knee after treatment was significantly less than that before treatment, the differences was statistically significant (P<0.05); The synovial thickness and the range of joint effusion after treatment were significantly less than those before treatment, the differences were statistically significant (all P<0.05). Conclusion High frequency ultrasound, which has the advantages of noninvasive, simple and accurate, can objectively and sensitively evaluate the curative effect of acupotomy on knee osteoarthritis, and has a certain clinical value.