Abstract: The authors question the main factors of influence reservoir conditions and oil-gas pool formation, by studying sedimentary microfacies,petrodistinction, diagensis, porous structural character and physical quality conditions.The main sedimentary microfacies of Triassic system Yanchang Formation incipient Chang-6 reservoir horizons in west area of Guoqi,Yanchang oil field is delta front subaqueous distributary channel deposits, and later Chang-6 mainly is distributary channel. Reservoir horizons are development,this area form reservoir horizons of low porosity and extra low permeability for diagensis influence,oil pool is the typical litho-petrolifertous-pool,distribution of oil pool is controlled by sediment ary micro facies and reservoir physical quality.