There developed several structure oil/gas traps or structure-lithology oil/gas traps in delta deposit of Eogene Shahejie Formation and Dongying Formation, Hongxing area. The study shows that the source rock of Sha 3 Member of Shahejie Formation developed extensively in Jiazhangsi sag, and the system tract of 3rd order sequence or sub-distributary, mouth bar, delta front sheet sandy and transgressive lacustrine mudstone of 4th order sequence formed 7-8 trap-scale reservoir and seal combinations in Sha 1 Member of Shahejie Formation and Dong 3 Member of Dongjing Formation, which constitute the basic condition to oil/gas trap.