ObjectiveTo summarize the clinical characteristics and treatment outcome of postoperative infection of knee joint ankylosis surgery caused by Finegoldia magna(F. magna).MethodsClinical data of one case of infection with F. magna after knee joint ankylosis surgery was analyzed retrospectively, relevant literatures at home and abroad were reviewed and analyzed.ResultsThe incisional wound didn’t heal after knee ankylosis surgery, anaerobic culture result of exudate was F. magna, after 4 weeks of treatment with susceptible antimicrobials cefoxitin and penicillin sodium, the incisional wound was dry and without exudation, patient healed well and was discharged from hospital.ConclusionClinical significance of anaerobic bacterial infection should be fully recognized, in bone and joint infection, especially when the common bacterial culture result is negative, the possibility of infection with anaerobic bacteria should be considered.