Abstract: In this paper, derived the formulas for calculating the stresses and deformations of concrete lining,steel lining and surrounding rock of high pressure underground conduit in which internal pressures are applied during different stages. These formulas are applicable to the cracks in different layers or different radial cracks in concrete lining and surrounding rock, also to the calculation of critical internal water pressure causing radial cracks in concrete and surrounding rock,and to the calculation of the radii within crack area. Compared with other similar ones,these formulas have higher precision and more extensive application.