Abstract: Objective To explore the effect of autologous platelet-rich plasma(PRP) combined with intra-articular hyaluronic acid(HA)injection in the treatment of knee osteoarthritis. Methods One hundred and fifty cases of knee osteoarthritis met criteria in our hospital was collected in March,2009 to March,2015.They were randomly divided into three groups:the group A,the group B and the group C.The general information of the three groups were comparable.The group A was given knee intra-articular injection of HA 6 ml,the group B was given knee intra-articular injection of PRP 6 ml,and the group C was given knee intra-articular injection of PRP 4 ml and HA 2 ml at 10 min afterwards,once a week for five weeks.The Western Ontario and McMaster American Universities Osteoarthritis Index score(WOMAC score),the International Knee Documentation Committee knee evaluation form(IKDC) score,Lequesne index,adverse reactions of three groups were recorded and analyzed before and after the treatment. Results The WOMAC score and Lequesne index of group C were lower than those in the other two groups,while the IKDC score were higher than the other two groups.The WOMAC,IKDC score,Lequesne index score of group B were superior than group A(P<0.05).Three patients of three groups were not found severe drug related adverse reactions during treatment. Conclusion PRP combined with HA can significantly control the pain and improve the joint function with high safety and efficacy.And it deserved clinical promotion.