Abstract: Objective To investigate the clinical effect of magnetic navigation retrograde interlocking intramedullary nail distal locking technique in the treatment of middle and lower femoral fractures. Methods A retrospective analysis of the patients with mid-lower femoral fractures who were admitted to our hospital from January 2017 to February 2019 and were followed up were divided into two groups：navigation lock group（group A）and mechanical aiming lock group（Group B），16 patients in Group A using electromagnetic navigation distal locking technology，22 patients in Group B using mechanical targeting distal locking technology.The following indicators were compared in the two groups：the success rate of the intraoperative distal one-time locking in the two groups，operation time，intraoperative blood loss，complication rate，fracture healing rate，fracture healing time，postoperative knee KOOS score. Results The success rate of distal locking once in group A was higher than that of group B，the operation time was shorter than that of group B，the intraoperative blood loss was less than that of group B，the incidence of complications was lower than that of group B，and Knee function postoperative score was better than that of group B，the difference was statistically significant（P<0.05）.The fracture healing rate in group A was higher than that in group B，and the fracture healing time was shorter than that in group B，but the difference was not statistically significant（P>0.05）. Conclusion Magnetic navigation retrograde interlocking intramedullary nail distal locking technique for the treatment of mid-lower femoral fracture has the advantages of short locking time，high efficiency and short radiation exposure time.

Key words: magnetic navigation, retrograde interlocking intramedullary nail, femur fracture