Objective To investigate how to treat distal femur fractures by using unicortical or bicortical screws in the proximal end of the less invasive stabilization system, LISS. Methods We took 115 Caprine right femurs, and all of them were created to simulate an AO/33-A3 fracture. All fracture models were fixed by a right 5 hole LISS Plate. They were treated differently by using unicortical or bicortical screws in the proximal end of the LISS plate, and at the same time, they were tested by withdrawal force and torsional force. Results When we using bicortical locked screws in the first and third hole of the proximal end of LISS, it reached the best balance with the distal end, and it created the biggest force to resist torsional force. Conclusion In this test, we can conclude，that using bicortical screws in the first and third hole of the proximal end of the LISS is the best way when we treat distal femur fractures AO/33-A3, it can reach the best balance with the distal end, and it created the biggest force to resist torsional force, and it can decrease the shearing force, torsional force, and then it can prevent hardware failure.