Abstract: Carboniferous strata,more than 1 000 m in thick in the area of Hexi corridor to Bayan Haot basin,is the coal measures of transitional phase,in which there are three kinds of hydrocarbon source rocks including dark mudstone,limestone,coal and carbonaceous mudstone.These source rocks are good gas source rocks and have a certain extent of oil-generating capability based on high abundance and typeⅡ2-Ⅲ of organic matters.And the most of them are the stage of "oil window" to dry gas.There are well source-reservoir-cap rock a ssemblages and suitable pet roleum pool-forming conditions in Carboniferous strata.Three districts are divided based on the petroleum geological condition,in which the Bayan Haot basin is the most favorable exploration district,the eastern Hexi corridoris a prospecttarget and the western Hexi corridor lacks hyd rocabon-bearing prospect.