Objective: The main purpose of correction craniosynostosis is to reopen cranial sutures with some bone slots in order to free the skull transformation with the brain development from the closed craniums. The skull rigidity is severely depend on the shape of bone slots, the main purpose of this paper is to obtain a right bone slots shape to decrease skull rigidity. Finite element method is utilized to calculate the stress distribution and deformation clouds of different schemes vary in bone slots shape. Methods: A Congenital craniosynostosis case is selected to design the surgery treatment plan. A modified PI-shape craniosynostosis correction plan is used and bone slots used for reconstruction the cranial suture are in variance to simulate the stress distribution and a best scheme is advanced. The cranial bone and endocranium 3D models are reconstructed from CT data, and then tetrahedron element models for finite element analysis are established. For the instantaneous stress take into account when the slots shape change, the viscoelastic material properties of the cranial bone and endocranium are ignored here. Results: The skull rigidity is apparent difference in kinds surgery schemes. Different bone slot shapes induce different cranium stress distribution and skull rigidity. Appropriate bone slots can make the cranium to win the right stress values and distribution and displacements. Conclusion: The results of stress distribution and deformation of cranial bone under the intracranial pressure after the correction craniosynostosis operation can be obtained by the finite element method. These results reflect the ability of the cranial bone expanding with the brain tissues growth. The finite element method is an available way, with which surgical prediction can be made to guide surgeons to make the decision of improving surgical treatment.