Objective To compare intramedullary nail, singal locking plate and double locking plate used in distal femoral fractures complicating total knee arthroplasty by finite element analysis. Methods The femur CT images of the volunteers and the data of the posterior stable knee joint prosthesis were imported into Mimics Research 16.0 and Geomagic Studio2012 to reconstructed entity model. In Cero3.0, the lateral locking plate of distal femur, common locking plate, intramedullary nail were designed and assemblied with the above model. Three models were constituted including the single plate group (distal lateral femoral locking plate + KIM 1 b fractures), the intramedullary nailing group (distal femoral intramedullary nailing + KIM 1 b fractures), the double plates group (distal lateral femoral locking plate + distal medial femoral locking plate + KIM 1 b fractures) .All models were divided into C3D4 units and given the material properties in Hypermesh 13.0. The boundary conditions were constrained on the distal end of femoral prosthesis and the load including 500N,500n+20N.M and 430N were added on the femur head in Abaqus6.14. The stress and maximum displacement at the femur fracture and the lateral condyle were calculated. Results (1) the stress in single plate group was significantly larger than the double plates group and the intramedullary nailing group(P<0.05), and there was no significant difference between the intramedullary nailing group and the double plates group (P>0.05). (2)the displacement of the fractures end were significantly difference among the three fixations (P<0.05), the single plate group were bigger than the intramedullary nail group and the double plates group (P<0.01), there were no difference in the intramedullary nailing group and double plates group (P>0.05). (3) The lateral femoral condylar stress in the single plate group was significantly higher than the intramedullary nailing group and the double plates group (P<0.05). there was no significant difference between the intramedullary nailing group and the double plates group (P>0.05), and also there was no significant difference in the medial femoral condylar among the three groups (P>0. 05). Conclusion The finite element analysis could objectively show the stress distribution of internal fixation, fracture end and prosthesis under different loads. Among the three fixtions, the intramedullary nail and double locking plate is not only beneficial to the stability of fracture ,but also could significantly reduce the stress on the lateral femoral condyle, and it is good for the stability of the prosthesis.