Stability of the large thin-walled absorption tower is essential to its safe operation. The large finite-element analysis software is adopted for parameterized modeling of the tower. It requires the internal pressure of the tower tube to be the load form of the partial yield on the tower, respectively considering the structural model displacement and the actual dent on the tower surface as the initial defect, and performing the nonlinear buckling analysis of the reinforced absorption tower structure. As is indicated, the yield load produces lesser effect on the initial defect. Meanwhile, when the structure yields critically, plastic deformation takes place in some part of the tower tube due to potentiation of the stiffening ribs. Moreover, stiffening ribs and wall thickness improve the stable load. With the increase of wall thickness, the load of critical stable internal pressure on the tower grows constantly but the critical stable load increases more slowly.