Objective To study correlation between the deformation and displacement trend of the lumbosacral vertebra (L1-S1) for two typical scoliosis spine under vertical load, so as to provide the mechanical basis of treatment and prevention of scoliosis in clinic. Methods The X-ray computed tomography (CT) imaging of two typical scoliosis spine (Lenke-4AN type and Lenke- 5CN type) were converted into 3D models，and their finite element models were then established and verified. The internal stress distribution and displacement variation of the models were calculated by the finite element software; the correlation between the lumbosacral vertebral structure and displacement of the spine was analyzed. Results Under the same boundary conditions and load cases, the stress and displacement for two kinds of lumbosacral vertebral models showed different trends. Due to its left-leaning and forward convex bending deformation as well as relatively large lordosis angle(60°) and smaller left-leaning angle (17.37°), the Lenke-4AN type lumbosacral spine produced slightly small forward convex displacement(8.18 mm) and relatively large left-leaning displacement (0.97 mm). The Lenke- 5CN type lumbosacral spine showed left-leaning and forward convex bending deformation as well, with relatively large lordosis angle (59°) and left-leaning angle (26.97°), so it produced more severe left-leaning (20.65 mm) and forward deformation (9.22 mm). Conclusions The deformation trend of lumbosacral vertebra is closely related to its structural characteristics, and different scoliosis lumbosacral vertebral structures will cause corresponding deformation trend. The research findings are important for the prevention and treatment of scoliosis.