Fusion has been the gold standard treatment for treating lumbar degenerative disc disease. Many clinical studies have demonstrated that adjacent segment degeneration was observed in patients over time. Various instrumentations of pedicle screw-based stabilization systems have been investigated using numerical approaches. However, numerical models developed in the past were simplified to reduce computational time. The aim of this study was to evaluate and to compare the biomechanical performance of rigid, semi-rigid, and dynamic posterior instrumentations using a more realistic numerical model. Three-dimensional nonlinear finite element models of the T11-S1 multilevel spine with various posterior instrumentations were developed. The intersegmental rotation, the maximum disc stress, and the maximum implant stress were calculated. The results indicated that the rigid instrumentation resulted in greater fixation stability but also a greater risk of adjacent segment degeneration and implant failure. The biomechanical performance of the dynamic instrumentation was closer to that of the intact spine model compared with the rigid and semi-rigid instrumentations. The results of this study could help surgeons understand the biomechanical characteristics of different posterior instrumentations for the treatment of lumbar degenerative disc diseases.