Abstract: Analyses of distribution and preservation characters of sealing rocks,sealing ability of main faults and chemical environment of formation water in wells have indicated that,there are differences of hydrocarbon preservation conditions among different regions in West Hubei and East Chongqing.Due to occurrence of complete sealing sequence,especially wide distribution of gypsum seal of the Lower Tria-ssic Jialingjiang Formation and poor development of fault structures,the Shizhu synclinorium is most favorable for hydrocarbon preservation.The Fangdoushan and Qiyueshan buried structures are both favorable for preservation,with the former better than the latter.Main part of synclinorium shows poor preservation conditions as the result of regional large fault opening and regional seal erosion.In the south of Lichuan synclinorium,seals are relatively complete and preservation conditions are good;while in the north,it is poor.