Abstract: When a building has a design or mechanical floor on the top.Sometimes the ratio of rigidity or shear capacity may exceed the limitation because the layer height is too short and the lateral rigidity is too strong.We should use finite element analysis to analyze the stress state and the deformation behavior of the elastic state of frequent earthquake and the elasticoplastic deformation behavior of rare earthquake to analyze the influence that the rigidity of the top structure layer effects the anti-seismic performance of the structure.