The axisymmetric thin walled housing model for the thin-walled housing of YPG-22500 flour pressure spray dryer was established, and the typical equation of energy method based on the thin-walled housing theory under the elastic-plastic deformation was listed, and the calculation method and condition on strain strength and deformation stiffness were also given. According to the assuming boundary condition on both ends of the housing and to the working environment of cycle fatigue and to the actual situation of materials line hardening, integrated the typical equation successively by the computer to obtain the numerical approximate solution matched the requirement and the key parameter curve, the conclusion which was very closed to the experimental results. That the ratio of the dimensionless variables u-(ε-) had little affection on the ratio of geometry parameters of the thin-walled housing and displacement between the both ends of it was pointed out in the paper. The problem of Elastic-plastic strain strength and the deflection calculation which were met in the industrial design of large thin-walled housing vessels under the pressure load was more reasonably solved.