Objective:The biomechanical properties of new type interlocking compression nail(NLN)and auto-branching in-terlocking compression nail(ALN)were compared to give us scientific evidences for clinical application.Methods:8pairs of fresh adult femora were used and fixed with these2instruments and plum-shaped intramedullary nail and C-K nail and biomechanical properties were compared.Results:The auto-branching interlocking compression nail is the best in the biomechanical properties compared with other devices(p<0.05).Conclusions:The Auto-branching Iterlocking compression Nail is better than other instruments because of better biomechanical properties and less no stress-shielding.It's a good device of the internal fixation of the unstable fracture of femoral shaft.