Abstract: Faults developed in all troughs in Huanghua Depression, and there are many types of structures in deep buried hills. Moreover, two sets of source rocks from the Second to the third member of Shahejie Formation or Carboniferous-Permian have higher thermal evolution degree and good reservoiring conditions. The Lower Paleozoic reservoir rocks are affected by three factors as the buried-hill overlying strata distribution range and different denudation degree, the faults development degree, and the underfl ow zone development degree. Also carbonate palaeokarst developed in some deeply buried hills. So deeply buried hills in Lower Paleozoic are favorable for hydrocarbon accumulation. Especially, there are fi ve factors favorable for reservoiring, that is, the earlier hydrocarbon charge stages, the smaller migration distance, the multi phases of oil/gas trapping, the great amount of gas in the deep and lower demand for accumulation conditions, and the superior oil/gas preservation conditions in later stage. However, the key factor of oil/gas enrichment in the area depends on the presence or growth degree of “oil-supplying” window. Two deeply buried hill structures of Nandagang and Gangdong are the major targets of oil and gas exploration, but the key problems to be solved are: there is an oil-supplying window in Lower Paleozoic carbonate strata in Nandagang fault and one side of Qibei fault or not; whether the traps in Ordovician buried hills are fulfi lled or not.