Abstract: Based on the theory of surrounding rock local deformation, the method of calculating the lining of the split vault underground by using the tangent elastic resistance of the surrounding rock at the bottom of girth is one more economical and rational in view of material economization. Here is in the paper presented a brief induction of calculation formula with actual calculation examples and an analytical comprarison between the various results worked out with different methods, which is of some value for reference to the calculation of the split vault and other spheric shell underground.