Abstract: Objective:To observe the effects of synovectomy on treating knee join osteoarthritis with debridement.Methods:One hundred and twelve patients with elderly degenerative osteoarthritis of knee were randomly divided into group A,which were treated with synovectomy under arthroscopy debridement as far as possible and group B were treated with synovectomy as few as possible.Results:All cases were followed up and evaluated by HSS knee score table.At 1 month and 6 months after operation,the HSS scores of two groups had no significant difference(P0.05).Conclusions:Synovectomy has good effects on the elderly knee join osteoarthritis treatment with debridement arthroscopy.The scope of the synovectomy should be reduced.