Abstract: In this article,we discuss the vertical characteristics of oil-gas oxygenation level and its preservation condition in petroleum basin.The exploration data indicate that oil-gas oxygenation level in Lunpola Basin,Tibet is about 1 300m.The main provement of the existence of oil-gas oxygenation level in this basin is the physical and chemical characteristics and chemical type of crude oil,as well as the largest depth of where the oxidized asphalt exists.According to the physical and chemical characteristics of crude oil,oil-gas distribution and the changes of seal characteristics in accordance with its depth,we divide the oil-gas preservation condition in Lunpola Basin into three belts vertically:the oxygenation zone less than (1 000)m,the intermediate zone from 1 000m to 1 300m,and the preservation zone more than 1 300m.