Abstract: Based on a project of denitrification, a complex structure contained a flue, a reactor and a bracket was analyzed. The flue exit and the reactor were chose as research subjects, and the effect of bracket deformation on the mechanical properties of the flue exit and the reactor was studied. It is indicated that the deformation distributions of the flue exit and the reactor change from symmetric into asymmetric when the influence of bracket deformation is considered, and the average deformation of them increases too, but the stress values and distributions of the flue exit and the reactor change slightly. Consequently, designing the flue exit and the reactor separately is acceptable when strength is the control factor.