Abstract: In order to solve the elastic-plastic unified solution of cylindrical cavity expansion under the combined action of two-dimensional unequal pressure stress field and shear stress, the stress function is expanded into trigonometric series, and the stress and displacement in elastic zone are derived. Then, the stress and displacement in plastic zone are derived by using the unified strength theory and associated flow rule. Finally, the elastic-plastic boundary is determined by the conformal mapping function, and then the constant coefficients of stress and displacement in elastic zone are determined by the least squares method according to the stress continuity condition at the elastic-plastic boundary. The new elastic-plastic unified solution provides a new framework for solving the problem of cylindrical cavity expansion, which extends the solution under the Tresca yield criterion and reflects the "non-circular effect" of cylindrical cavity expansion. The correctness of the solution is verified by comparing with the complex function method and experimental values, and the influences of various parameters on the elastic-plastic boundary, stress and displacement is analyzed.