Abstract: Abstract：Based on a study of main factors controlling hydrocarbon pooling of Quan4 Formation in Longxi area of Songliao basin, the authors hold that oil and gas generated from hydrocarbon source rock of Qing1 formation mainly migrate into Quan4 Formation in two ways. One is the downward migration of oil and gas generated from hydrocarbon source rock of Qing1 Formation along the faults into Quan4 Formation under the large below-source pressure difference. The large below-source pressure difference results from abnormal pressure of Qing1 Formation formed by compaction and hydrocarbon generation and negative pressure of Quan4 Formation generated along with fault activity. The other one is the lateral migration of oil and gas generated from hydrocarbon source rock of Qing1 Formation into Quan4 Formation under the conditions of upward-inclining lateral connection of hydrocarbon source rock of Qing1 Formation to Quan4 Formation caused by fault activity. The activity of Aogula-HaJahai faulted zone has formed the regional syncline to its west, which is not conducive to migration and accumulation of oil and gas. The eastern area of Aogula-HaJahai faulted zone is a slope, which is favorable for lateral migration of oil and gas. The activity of Aogula-HaJahai faulted zone caused the lateral connection of the mudstone of Qingshankou Formation to the sandstone of Quan4 Formation in the upward inclining direction on the western side of Aogula-HaJahai faulted zone, which is conducive to accumulation of oil and gas. A large number of fault-lithologic oil and gas pools were formed in the eastern area of Aogula-HaJahai faulted zone.