Abstract： Objective： To observe the clinical effect of electro- acupuncture combined with sodium hyaluronate for knee osteoarthritis complicated with joint effusion， and its effect on levels of matrix metalloproteinase(MMP)- 3， MMP- 9 and MMP- 13 in synovial fluid. Methods： A total of 90 cases of patients with knee osteoarthritis complicated with joint effusion were selected and divided into the combination of acupuncture and medicine group，the medicine group and the electro- acupuncture group according to the random number table method， with 30 cases in each group. The combination of acupuncture and medicine group was treated with electro-acupuncture combined with injection of sodium hyaluronate in articular cavity，the medicine group was simply treated with injection of sodium hyaluronate in articular cavity， and the electro- acupuncture group was simply treated with electro- acupuncture. All groups were treated for five weeks. The levels of MMP-3，MMP-9 and MMP-13 in synovial fluid and the scores of quality of life before and after treatment and the clinical effects in the three groups were compared. Results：The total effective rate was 96.67% in the combination of acupuncture and medicine group，higher than those of 76.67% and 73.33% in the medicine group and the electro-acupuncture group (P＜0.05). After treatment， the levels of MMP- 3， MMP- 9 and MMP- 13 in synovial fluid in the three groups were decreased when compared with those before treatment(P＜0.05)，and the levels of MMP-3， MMP-9 and MMP-13 in synovial fluid in the combination of acupuncture and medicine group were lower than those in the medicine group and the electro-acupuncture group(P＜0.05). After treatment，the scores of sleep，spirit and activities of daily living in the three groups were increased when compared with those before treatment(P＜0.05)，and the scores of sleep，spirit and activities of daily living in the combination of acupuncture and medicine group were higher than those in the medicine group and the electro-acupuncture group(P＜0.05). Conclusion：Electro-acupuncture combined with sodium hyaluronate has a better curative effect in treating knee osteoarthritis complicated with joint effusion than the simple treatment of electroacupuncture or sodium hyaluronate. It can significantly reduce the levels of MMP- 3，MMP-9 and MMP- 13 in synovial fluid and improve quality of life of patients.