Abstract: Two periods of hydrocarbon inclusions are observed in the Jurassic Ahe formation of Dibei gas reservoir, including the hydrocarbon inclusions of period Ⅰ with yellow fluorescence and the inclusions of period Ⅱ with blue fluorescence. The analysis on the optical characteristics and components of the inclusions shows that the inclusions of period Ⅰ are mature intermediate oil and those of period II are mature-over mature light condensate oil. On the basis of oil-source rock correlation, it is considered that the major source rocks of the two periods of hydrocarbon inclusions are the Triassic lacustrine source rocks in Yangxia sag. The results of temperature measurement, capture depth calculation and burial history restoration for the conclusions indicate that the inclusions of period Ⅰ formed during the early-medium deposition period (17—10 Ma) of the Miocene Kangcun formation, and the inclusions of period Ⅱ formed in the late deposition period of the Miocene Kangcun formation to the medium deposition period of the Kuche formation (10—5 Ma). The Yiqikelike tectonic belt deposited rapidly since Miocene, resulting in the multi-period and continuous reservoir accumulation