Abstract: With regard to the insufficient researches on the reliability of the existing seismic analysis methods for underground structures for the seismic design of large-scale underground structures, three site classifications are designed according to the relevant seismic design codes, and the characteristics of seismic deformation of the interaction system are analyzed under 84 conditions by using the finite element method. The results show that when the peak acceleration of input earthquake wave is larger than 0.2g with any kind of site classification or when the site classification is Ⅳ under very small peak acceleration, the soil-structure interaction coefficients are all smaller than one, which means that the lateral soils with large deformation may push the underground structure to be deformed maximally. In other word, the large deformation of the surrounding soil foundation is unfavourable to the seismic performance of the large underground structures. On the contrary, the maximal deformation of the underground structures should be constrained by the surrounding soils, which is favourable to the seismic performance of the underground structures. Meanwhile, the effect laws of the site classification and the properties of input ground motion on the seismic deformation of the large underground structures are also analyzed.