Objective To investigate the advantages and the clinical outcomes of the treatment of comminuted inferior femoral fractures with combination of supracondylar locked intramedullary nail and shape memory block hoop internal fixator under arthroscopy. Methods From June 2002 to December 2004, 12 cases of comminuted inferior femoral fractures were treated(9 males, 3 females). Of them, 5 cases were classified as type B and 7 cases as type C according to AO classification . All cases were treated with combination of supracondylar locked intramedullary nail and shape memory block hoop internal fixator under arthroscopy. In 12 cases of one-stage bone grafting, there 5 of autologous cancellous bone grafting and 7 allo-freeze drying bone grafting.Results With a follow-up of 6 to 18 months, all fractures healed within 3 to 6 months. There were no infection and nonunion. The function of all the knees joint was excellent. According to Noye’s criterion for knee scoring, the results were excellent in 9 cases and good in 3 cases; the excellent and good rate was 100%. Conclusion It is a good method to treat comminuted inferior femoral fractures with combination of supracondylar locked intramedullary nail and shape memory block hoop internal fixator under arthroscopy. It has many advantages of less injury to knee joint, good anatomic reduction and reliable fixation.