Abstract: To evaluate the biomechanical stability of femoral shaft fracture fixation using different locking plates combined with different screw layout, for two different fracture settings, we build six groups different length locking plate combined with different screw number and different screw layout, fix with the fracture models respectively, and use the biomechanical finite element method to analysis the models. Then we attain the axial displacement and equivalent stress distribution of the internal fixation system under the action of axial load. The research shows that filling relatively softer material in femoral fracture can guarantee the stability of the internal fixation system, the long plate combined with less screw layout is obviously better than the short plate combined with the all screw layout, the same length plate combined with the selective screw layout is more effective than combined with the all screw layout. And plate combined with screws fixed in four threaded hole of distal fracture make the screw system stress disperse, and avoiding screw fixed in proximal fracture can alleviate the stress concentration of screws.