According to the failure features of concrete lining under seepage load，a three-dimensional numerical coupling analysis of seepage field and stress field is made on the fracture regulation of the high pressure conduit lining. Based on cracking characters of concrete lining

the computation formulae of crack width for concrete lining under seepage load are given. According to the bearing capacities of the concrete lining at the instant of cracking

the seepage load can be divided into two parts during computation. The preceding part of the load

smaller than that critical load

can be applied to the concrete lining structure once; and the latter part which is larger than the critical value adopts gradient iterative method. By this way

the rock slope stability taking into account seepage interaction effects can be analyzed preferably. Through computing practical engineering

the infection of seepage induced by high pressure water inside conduit is demonstrated. An efficient computation method is provided for the design of underground conduit with high internal water pressure.