Objective To compare the biomechanical effects of n-HA/PA66 vertebral body cage and percutaneous vertebroplasty for treating osteoporotic vertebral fracture, so as to provide theoretical foundations for clinically choosing operative approach and numbers of n-HA/PA66 cage. Methods Based on finite element models of normal vertebral T11-L3, four finite element models of vertebral T11-L3 with n-HA/PA66 cage implanted by different approaches (transversus approach A, B and psoas major muscle approach A, B) were established. Two controlled models without intertransverse ligaments were also built. Besides, two finite element models of osteoporotic vertebral T11-L3 with injection of 1.8 mL or 3.6 mL bone cement were built, respectively. The loads of 500 N and force torque of 7 N·m from different directions were applied on nine models, to calculate and analyze the displacement and stress of the osteoporotic vertebrae during standing, extension, anteflexion, lateral bending, and rotation, and to investigate the biomechanical effects from two kinds of osteoporotic vertebral fracture treatment on vertebral body. Results Under the same loading, bone cement could lead to a larger stress increase while a smaller displacement decrease in vertebral body compared with n-HA/PA66 cage. The model with n-HA/PA66 cage implanted by psoas major muscle approach A (namely, a cage was implanted through psoas major muscle) had the minimal increase in vertebral stress while the maximum decrease in displacement. Conclusions In order to reduce the risk of the additional fracture due to stress increment and recover the stiffness of osteoporotic vertebrae, clinicians are suggested to implant one n-HA/PA66 cage through psoas major to treat the osteoporotic vertebral fractures.