Based on comprehensive analyses of reservoir features，source rocks and carrier systems，this paper summarizes differences ofhydrocarbon accumulation among threem iddle and large oilfields（the JZ20-2，JZ25-1S and SZ36-1oilfields）in the Liaoxi Low Uplift，the Liaodong Bay area.For the JZ20-2oilfield，the hydrocarbon accumulation pattern is singlem igration direction and double sources.Separated by the regional overpressure cap rocks consisting of the lower part of the2 nd member and the3 rd member of the Dongying Formation，the upper oil pool in the Dongying Formation has normal pressure and its hydrocarbonswere generated by source rocks in the3 rd member of the Dongying Formation in the northern Liaozhong subsag，andm igrated along the delta sandbodies in the2 nd member of the Dongying Formation，while the lower condensate gas pool in the Shahejie Formation and buried hill has overpressure and the hydrocarbons were generated by source rocks in the Shahejie Formation in the northern Liaozhong subsag and m igrated along unconform ities.For the JZ25-1S oilfield，the hydrocarbon accumulation pattern is doublem igration direction and m ixed sources.Hydrocarbons sourced from the Liaoxi sag m igrated vertically to the Liaoxi low uplift along the Liaoxi-1and Liaoxi-2boundary faults，and hydrocarbons sourced from the Liaozhong sag m igrated laterally along unconform ities and sandbodies in the eastern slope. Finally，these hydrocarbonsm ixed and accumulated in the sandstone of the2 nd member of the Shahejie Formation in the JZ25-1S structure and the reservoirs in Archaeozoic buried hills.For the SZ36-1oilfield，hydrocarbon accumulation pattern is single m igration direction and single source.Hydrocarbon sourced from the southern Liaozhong subsagm igrated in large scale and long distance along the faults connecting source rocks and reservoirs and delta sandbodies to sandstones in the2 nd member of the Dongying Formation in the SZ36-1structure.