Objective To compare the biomechanical characteristics of the new retrograde intramedullary nail, common femoral retrograde intramedullary nail, and medial femoral condyle locking plate in the treatment of type A distal femoral fractures by finite element analysis, and to study the advantages of retrograde intramedullary nail on medial femoral condyle.Methods Design a new new retrograde intramedullary nail on medial femur condyle. A CT scan was performed on the lower limb bone of a male volunteer, and a three-dimensional model of the femur was established using soft. The model was then segmented to create a three-dimensional model of a femoral distal A2、A3 type fracture. The three dimensional models of internal fixator were established. The small and standard retrograde intramedullary nailing on medial femoral condyle, common femoral retrograde intramedullary nailing, locking plate on medial femoral condyle were used for internal fixation on A2 type fracture. A3 type fracture was fixed with one of the above internal fixators combined with lateral condylar plate respectively.The axial load of 600 N and the torsional load of 4N·m were applied to the models. The displacement and stress of femurs , the displacement and stress of internal fixators, the micro-momentum between the internal fixator and the bone, the relative displacement of the two fracture broken ends were observed in each group. Results Among the A2 and A3 type fractures under axial loads, the standard (combined) group had the smallest peak displacement and peak stress of the femur and internal fixation. Among the A2 and A3 type fractures under torsional loads, the standard group (combined) had the smallest peak displacement of the femur and internal fixation. The relative displacement of the two broken ends in the standard combined group was the smallest. Conclusion Compared with femoral medial condylar locking plate and common retrograde intramedullary needle, the new retrograde intramedullary needle on medial femur condyle has mechanical advantages of reducing stress concentration and reducing the risk of internal fixation failure,can be used alone for distal femoral A2 type fracture, or in combination with the lateral condylar plate to fix distal femoral A3 type fracture.