Objective To investigate the effect of posterior pedicle screw instrumentation and determine the impact of alternative surgical strategies to provide guidance for the operation planning. Methods A detailed three-dimensional finite element model of a 40° scoliotic lumbar with pedicle screw instrument were constructed by using the commercial finite element software ANSYS. The geometry of the model was extracted from a computed tomography reconstruction. The correction process including rod rotation and spring-back was simulated with rigid body dynamic software ADAMS. Reaction loads on implant as well as stress distribution of lumbar spine were acquired through the correction simulation. Results The maximal reaction forces were in the range of 196-1099 N. Few bony elements around the screw exceeded the ultimate strength of 120 MPa. Conclusions Idiopathic scoliosis could be well treated by posterior pedicle screw instrumentation with the safety of vertebrae ensured. Different surgical strategies could be considered to conserve implanted lumbar spine level and to improve the surgical quality.