Abstract: Through regional geological analysis of Irrawaddy basin and petroleum geological condition analysis of Sarin sag,Sarin sag is believed to be of superior conditions for hydrocarbon accumulation.Eocene series delta front subfacies shale and mud swamp subfacies coal shale has strong ability of hydrocarbon generation,which provides rich material base for oil and gas enrichment,in combination with the thrust fault zone,it can jointly control the hydrocarbon distribution.Good generation-reservoir-caprock association,successive traps and hydrocarbon transportation systems constituted by faults,permeable zones and unconformity surface can provide migration channels and space for oil and gas accumulation.Good reservoir-forming assemblages can form Oligocene-Miocene the lower generation and upper storage pattern and the main oil sands body can form a multiple layered reservoirs.The waited-to-be-found Oligocene self-generating and self-preserving reservoirs are mainly lied in the thrust fault footwall,and it has been found in Taben formation of Eocene series,which is located in D block of the northern sag.Similar formation and structural trap characteristics have been found in Sarin sag and therefore,it has a good exploration prospect.