In the paper, the sandy pebble soil which was most massively distributed in Sichuan was used as foundation. The finite element model of mega frame structure including the superstructure, raft foundation and the sandy pebble groundwork was built by applying the finite element analysis software ANSYS. The response of the mega frame structures under dynamic load was analyzed to study the mechanical properties, deformational properties and the interaction between mega frame structures and the sandy pebble soil. At last, in the same structural style and same foundation soil, the dynamic behaviors of such structure which take no account of the interaction between mega frame structures and the sandy pebble soil was compared with structure which took account of the interaction. The research in the paper could provide certain reference value for the future engineering.