Objective: Basedon biomechanical characteristics, comparison of mechanical stability between Intramedullary Fibular Allograft together with Cannulated Screw Fixation(Modified Operation Method) and Cannulated Screw Fixation Alone(Conventional SurgeryMethod) in the treatment of young and middle-aged Pauwels Ⅰ, Ⅱ, Ⅲ type.Method:Construction of Pauwels Ⅰ, Ⅱ, Ⅲ femoral neck fracture model with treatment of conventional surgery method(3S) and modified operation method(SFS) by using Mimics10.01 based on CT data; Stress analysis among the weight-bearing area of the femoral cortical bone shell, the top of the implant, the proximal femoral crown, and the end of femoral neck fracture.Stress distribution of 3 different directions of the cortical bone shell of the femoral head and femoral neck fracture surface was analyzed, the maximum principal strain cloud map of the coronal position of femur and the line graph of displacement reaction forcing position were drawn according to predicted data. Result: The stress distributionin cortical bone-shell bearing region showed that internal fixation of femoral neck was not different from that of normal condition. According to stress distribution pattern of the femoral proximal coronary, Pauwels Ⅰ SFS and 3S principal stress pattern remains still basically transmits from the weight-bearing region of the femoral head to the femoral moment,while Ⅱ SFS, Ⅱ 3S, Ⅲ SFS, Ⅲ 3S appear stress concentration phenomenon at the border of implants and fracture surface. And the shear stress distribution in the three directions(S12,S13,S23)on the cortical bone shell of the femoral head and the fracture surface of the femoral neck showed that femoral neck fractures treated with SFS internal fixation was superior to or similar to 3S. The displacement of 3SⅢ and 3SⅡ were greater than femoral neck fracture with SFS, especially 3SⅡ. But Pauwels Ⅰshowed the opposite results on the displacement that reaction forces apply position.Conclusion: Modified operation method (SFS) is more suitable for large angle in femoral neck fracture (Ⅱ and Ⅲ);by contrast, Pauwels Ⅰ is more inclined to useconventional surgery.