To study the influence of AORI type I and II tibial plateau defect on the stability of tibial prosthesis ,and provide the basis for choosing the appropriate reconstruction method in clinic. Methods：The volunteers'' knee joint was scanned by CT and the knee joint prosthesis were scanned by EinScan-S laser scanner to obtain the point cloud of the model, and then the 3D model was established in Mimics 17 and Geomagic2002 software. All the models assemblied in CERO4.0 and Hypermesh13.0. According to AORI classification, the finite element model of with defect area 10%, 20%, 30% and 40% were established respectively. The maximum stress and displacement of the tibial prosthesis in each model were analyzed by loading the pressure load and torsion load in ABAQUS 6.1. Results ①Under the pressure load, the maximum stress between 30% model and 40% model of the tibial defect was statistically significant (p<0.05) in the non inclusive defect model of the medial tibia. The maximum stress of the 40% model was significantly greater than the other three models in the inclusive defect model and the tibial lateral model, the difference was statistically significant (p<0.01). ②Under torsional loading, the maximum stress in 40% model were significantly larger than those of the other three models (p < 0.01).③The maximum displacement of tibial prosthesis was concentrated in the distal part of the prosthesis. In the non inclusive defect and inclusive defect model of the tibial plateau, the maximum displacement of the 30% model was significantly greater than that of the 10% model and the 20% model (p<0.05), while the 30% model and the 40% model were also statistically significant (p<0.01). The maximum displacement of 40% of the models was significantly greater than that of the other three models (p < 0.01).Conclusion：The tibial plateau bone defect significantly affects the stability of tibial prosthesis. The defect of 20%-30% could be rebuilt. but 40% or more bone defects, lengthening rods should be added to enhance the stability of the prosthesis and avoid the failure of bone reconstruction.