Abstract: Objective: To compare the maximum flexion of knee joint after total knee arthroplasty（TKA） using high flexion prosthesis（PFC-RPF） and traditional rotating platform prothesis（PFC-RP）. Methods: A total of 232 patients（346 knees） with osteoarthritis underwent TKA using PFC-RPF or PFC-RP prosthesis.Patients were randomized to 10 groups.Groups AⅠf/BⅠf /AⅡf /CⅡf/DⅡf underwent TKA using PFC-RPF,while groups AⅠ/BⅠ/AⅡ/CⅡ/DⅡunderwent TKA using PFC-RP.The hyperextension and hyperinflexion of lateral knee joint were observed on radiograph and compared with the ibiofemoral angle. Results: A significant difference was observed in the maximum flexion of knee joint between groups AⅠf /AⅠand BⅠf /BⅠ.However,no significant difference was found in the maximum flexion of knee joint between groups AⅡf /AⅡ,CⅡf /CⅡand DⅡf /DⅡ. Conclusion: The flexion of knee joint is better after unilateral knee replacement using PFC-RPF than with PFC-RP.However,the flexion of knee joint is not improved after bilateral knee replacement.