To explore the correlation between the functional evaluation of knee joint after the primary TKA and the use of fixed femoral valgus cut angle during the operation. [Methods] From October 2017 to October 2018, 43 osteoarthritis patients with primary simple knee arthroplasty were enrolled, follow-up period of at least 1 year, and postoperative femoral valgus cut angle (VCA) and knee function HSS score were recorded. The correlation between the fixed VCA and the HSS score was analyzed by linear regression analysis. [Results] Distal femur osteotomy was performed by a fixed 5° VCA. Postoperative VCA showed a little fluctuation ranging from 5.0 to 7.9°. The postoperative VCA was no significant difference among different prosthesis groups (P > 0.05), and there was no significant difference in knee function score of HSS among three groups (P > 0.05). Stratified by VCA, there was no significant difference in knee HSS score in different VCA groups (P > 0.05), and there was no correlation between HSS and VCA in each group (P > 0.05).There was no direct correlation between total HSS knee function score and VCA of fixation femoral valgus osteotomy (P > 0.05). [Conclusion] The knee function evaluation after primary simple TKA was not associated with the use of fixed femoral valgus cut angle intraoperatively.