Great　efforts　have　been　made　in　investigating　the　effect　of　buried　depth　influencing　the　seismic　response　of　rectangular　underground　structures,　however,　a　consensus　hasn＇t　been　achieved　yet.　This　paper　presents　numerical　studies　on　seismic　behaviors　of　rectangular　underground　structures　at　different　buried　depths,　and　aims　to　illustrate　the　rule　that　buried　depth　effects　the　seismic　response　of　underground　structures.　Firstly,　to　describe　the　softening　and　over-consolidated　propertied　of　soils,　a　3D　elastoplastic　constitutive　model　was　developed.　Then　the　stress　states　of　the　underground　structures　and　surrounding　soils　before　earthquakes,　which　were　one　of　the　most　important　issues　and　generally　ignored　in　the　previous　studies,　were　discussed　detailedly.　Afterwards,　three-dimensional　numerical　models　for　nonlinear　earthquake　response　simulations　of　underground　structures　were　built,　and　the　seismic　responses　of　the　rectangular　structure　at　various　buried　depths　and　under　multiple　ground　motions　were　simulated.　And　vertical　and　horizontal　deformations　of　both　the　underground　structures　and　surrounding　soils　were　systematically　studied.　Consequently,　a　buried　depth　of　the　strongest　seismic　response　for　underground　structures　was　proposed　based　on　the　exploration　of　the　relations　between　the　buried　depth　and　the　structural　distortions　of　underground　structures　as　well　as　the　ground　subsidence.　Finally,　pertinence　suggestions　were　proposed　for　the　seismic　design　of　underground　structures　at　different　buried　depths.