Objective:To observe the clinical efficiency of low-frequency electro-acupuncture in the treatment of knee osteoarthritis  Methods:Eighty subjects were randomized into treatment group and control group (40 cases in each group), and treated respectively by low-frequency electro-acupuncture and Diclofenac Sodium Sustained Release Capsules, with a course of 28 days. The visual analogue scale(VAS) and the Lysholm knee scoring scale(LKSS) were used to observe the knee pain severity and function of knee joints  Results:After treatment, the VAS scores in both groups were significantly lowered(P<0.01), with lower scores in the treatment group than in the control group(P<0.05); the LKSS was increased in the treatment group after treatment(P<0.01), with high score in the treatment group than in the control group(P<0.05)  Conclusion:Low-frequency electro-acupuncture is effective to relieve pain and improve joint function in knee osteoarthritis.