The finite element analysis software ABAQUS is used to analyze the buckling of solid rocket motor shell under external pressure. By comparing the theoretical formula calculation results with the finite element calculation results， the error between the finite element calculation results and Mises formula calculation results is within 2.7% when the length-diameter ratio of the light shell is greater than 8， which verifies the accuracy of the finite element calculation method. The buckling performance of shells with different centering parts is analyzed by finite element method. It can be seen that compared with increasing the axial length of centering parts， increasing the thickness of centering parts can improve the buckling resistance of shells more obviously. The closer the centering position is to the middle of the shell， the better the buckling resistance of the shell is. In this paper， under the size constraint of centering parts， the critical instability pressure increases by 36.1% from one centering part in the middle to three centering parts uniformly distributed.