Abstract: The western sag and eastern sag in Liaohe depression have the same tectonic setting, but the buried hill hydrocarben of the western sag is more abundant than the eastern sag. In this paper, the buried hill hydrocarbon accumulation conditions in these two sags are analyzed and shown that the western sag developed additional set of source rock of the Es4 and the quality of the Es3 source rock is better than that of the eastern sag, which makes the western sag be superior to the eastern sag in source rock condition; the lithology of the buried hill in the western sag is dominated by carbonate rock and metamorphic rock, while that in the eastern sag by clastic rock, the former is bettern than the latter in reservoir quality or petrophysical property; the western sag develops early faulting ? early ceasing and inherited active faults, while the eastern sag only develops the inherited active fault, which allows the western sag to be of better buried hill trap and hydrocarbon?charging conditions in slope area than the eastern sag. It is the development and quality of the source rock, the reservoir petrophysical property and the diffrences of the faulting activity that controll the enrichment of oil and gas in buried hills of these two sags