With the aging population, intertrochanteric femur fracture in the elderly has become one of the most serious public health issues and a hot topic of research in trauma orthopedics. Due to the limitations of internal fixation techniques and the insufficient mechanical design of nails, the occurrence of complications delays patient recovery after surgical treatment. Design of a proximal femur bionic nail (PFBN) based on Zhang’s N triangle theory provides triangular supporting fixation, which dramatically decreases the occurrence of complications and has been widely used for clinical treatment of unstable intertrochanteric femur fracture worldwide. In this work, we developed an equivalent biomechanical model to analyze improvement in bone remodeling of unstable intertrochanteric femur fracture through PFBN use. The results show that compared with proximal femoral nail antirotation (PFNA) and InterTan, PFBN can dramatically decrease the maximum strain in the proximal femur. Based on Frost’s mechanostat theory, the local mechanical environment in the proximal femur can be regulated into the medium overload region by using a PFBN, which may render the proximal femur in a state of physiological overload, favoring post-operative recovery of intertrochanteric femur fracture in the elderly. This work shows that PFBN may constitute a panacea for unstable intertrochanteric femur fracture and provides insights into improving methods of internal fixation.