[en] A three-dimensional inhomogeneous magnetohydrodynamic equation is investigated numerically. It is found that a spatially ordered structure is formed at a saturated energy level by the excitation of the convective cell modes due to the three-dimensional nonlinear mode coupling. It is shown that the saturated energy level and radial plasma flux are proportional to the magnitude of the background density gradient. The experimental observation of a self-organized coherent structure in a finite-β collisional edge plasma is expected