Objective To investigate the clinical efficacy of a needle knife in treating knee meniscus injury. Methods One hundred patients with knee meniscus injury (112 knee joints) were randomly allocated to treatment and control groups, 50 cases each. The treatment group received needle knife therapy and the control group, an injection of sodium hyaluronate injectio into knee joint cavity. The main clinical symptoms and signs around the knee joint were observed and the knee function score was recorded in the two groups before and after treatment. the clinical therapeutic effects were evaluated in the two groups. Results There were statistically significant differences in pre-/post-treatment main clinical symptom and sign index (pain score, swelling score, activity score and tenderness index score) difference values between the two groups (P<0.05). There were statistically significant differences in the main clinical symptom and sign index difference values at follow-up compared with before treatment between the two groups (P<0.05). There was a statistically significant differences in the knee function score after treatment and at follow-up compared with before treatment in the two groups (P<0.01,P<0.05). There was a statistically significant differences in the knee function score between the treatment and control groups after treatment and at follow-up (P<0.05). Post-treatment excellence rate and total efficacy rate were 94.0%and 100.0%, respectively, in the treatment group and 72.0%and 98.0%, respectively, in the control group. There was a statistically significant differences in post-treatment excellence rate between the two groups (P<0.05). Follow-up excellence rate and total efficacy rate were 96.0% and 100.0%, respectively, in the treatment group and 76.0% and 98.0%, respectively, in the control group. There was a statistically significant differences in follow-up excellence rate between the two groups (P<0.05). Conclusion Needle knife therapy is an effective way to treat knee meniscus injury.