A hydraulic pressure tunnels structure is very complex. The work of FEM of pre-or post-processing is too much. So it is very important to find an effective simplification algorithm. When the hydraulic pressure tunnel is pressed by water, the concrete of tunnel transfers the pressure to the surrounding rock mass, and it also is pressed by the rock reaction force at the same time. In the analysis of FEM, much attention is paied to the strain and stress of the lining and surrounding rock mass nearby. The rock mass is regarded as isotropically continual body. Through simulating rock reaction force, the stress analysis of hydraulic pressure tunnel can be converted into thick-wall cylinder pressurized both inner and outer,so the preparation and calculation work using the thick-wall cylinder in stead of the lining and surrounding rock mass nearby are much decreased.