Wendong sag，one of the small Mesozoic-to-Cenozoic lacustrine rift basins locating in the Luxi uplift，deposits thick Paleocene mudrocks with shallow burial depth and high exploration value. Vertically，development features and enrichment factors of shale oil of the Dawenkou Formation within the sag was analyzed on the basis of data of Well Wenye No.1 drilled by China Geological Survey. The drilling results of Well Wenye No.1 show that about 500 m thick of source rock develops at the middle-to-upper member of the Dawenkou Formation near the subsidence center of Wendong sag. Hydrocarbons accumulate in the ways of shale oil with oil content generally greater than 1.5%. Two shale oil-rich intervals having high hydrocarbon generation potential are found at 440-560 m and 700-820 m underground. The level of vertical enrichment for shale oil in this region depends on depositional setting，TOC abundance and development level of fractures（beddings）. Evidence shows semi-deep to deep lacustrine setting is favorable for organic matter preservation which provides fundamental material for hydrocarbon generation；the abundance of organic matter has a positive relationship with oil content，which determines the hydrocarbon generation potential；fractures（beddings）provide better porosity and permeability and make the accumulation of oil possible.