Abstract: The geological conditions, hydrocarbon distribution and enrichment regularity in the Wan'an Basin were systematically analyzed based on the latest seismic and test data. Some new understanding of oil and gas geological characteristics and resource potential were obtained. The Wan'an Basin experienced two tectonic evolution stages: fault depression phase and depression phase. Inshore limnetic, shore delta, fan delta, coastal-shallow sea, and bathyal facies deposited. Sediments are from west to east. The major source rocks are mudstone, shale, coal and coal-bearing mudstone in the Oligocene and Miocene, which mainly distributed in the central and northern depressions. There are three kinds of reservoirs, respectively the sandstones of Oligocene to Pliocene, the carbonate rocks of Middle to Upper Miocene, and the bed rocks of pre-Tertiary. There are two sets of regional cap rocks, the Pliocene-Quaternary and the Upper Oligocene-Lower Miocene. There are three favorable oil-and-gas regions, the west, the central and the southern zones. Oil and gas potential of the Wan'an Basin is tremendous, and the geology resources of oil and gas are 29.38×10⁸ t and 34 897×10⁸ m³, respectively.