In Wangguantun area of Huanghua Depression with considerable potential of exploration，many oil and gas wells with high yield have been drilled in the Mesozoic and Paleozoic reservoirs. Based on the geological，geochemical，seismic，well logging and log data，the hydrocarbon accumulation conditions such as source rocks and reservoir-cap rock assemblages in Wangguantun area were analyzed. Through fluid inclusion technology and fluorescence microscopy of asphalt，the oil and gas accumulation stage and period were determined. Meanwhile，the hydrocarbon accumulation process was restored and its pattern was established. The results show that the Wangguantun area has good hydrocarbon generation conditions，in which Ek2 is the main hydrocarbon supply series of strata，with a small amount of the Carboniferous and Permian oil and gas sources mixed. High-quality reservoirs and regional cap rocks are well preserved，with regional cap rocks of mudstone，gypsolyte，and coal seam developing in the Mesozoic and Paleozoic as well as the overlying Cenozoic. The transport conditions are superior，as the hydrocarbon supply window exists between source rocks and reservoir，which are connected by the composite hydrocarbon transporting system consisting of fault with unconformity and sand body. Oil and gas from the Carboniferous and Permian source rocks are migrating into sandstone and underlying Ordovician carbonate rocks to be entrapped，while oil and gas from Ek2 source rocks are injected into the Mesozoic and Paleozoic through faults to be entrapped. As a whole，the buried hills of the Mesozoic and Paleozoic in Wangguantun area are featured by“multi-directional hydrocarbon supplies，composite transportation，and near-source accumulation”.