Objective To test the mechanical properties such as stiffness and strength of a new proximal femoral nail antirotation (PFNA) with three-dimensional finite element method and analyze its stress and strain distributions before and after the femur intertrochanteric fracture healing. Methods The three-dimensional model of PFNA was established by UG NX and the CT images were preprocessed by MIMICS. The finite element model of intertrochanteric fracture and fracture healing were developed for numerical simulation. Results Before the fracture healing, the maximal Von Mises stress was up to 663 Mpa at the location of fracture and that near the locking bolt was only 113 MPa after PFNA implanted. After the fracture healing, the maximal Von Mises stress occurred at the blade-nail interface. Obvious stress concentrations appeared near the locking bolt on the femur shaft. Conclusions The PFNA should be taken out because the femur shaft fracture often occurred at the location of the locking bolt after healing.