A two dimension atypical elastoplastic model was introduced to study the problem of rock pressure in engineering excavation under high ground stress. This model was established on the base of description of slip line grids in local orthogonal curvilinear coordinate, in which discontinuity of displacement field in excavation was depicted with a combination of two smooth functions. A analytic model for rock pressure of circular opening was given through strict mathematic deduction. Rock pressure of opening is quite less than ground stress, which demonstrates that bearing capability of surrounding rock plays an important role. It is concluded that depth, size and shape of opening, physical and mechanical properties of surrounding rock, and support rock pressure of circular opening have great influence on rock pressure.