Abstract: Based on sophisticated observations on cores,thin sections and analysis on logging curves,combined with through study on sedimentary characteristics,such as lithologic types and associations,palaeobiologic fossils and textures,sedimentary structures,and considering regional sedimentary background,it is recognized that Jialingjiang Formation in Qianwei area is characterized by semi-restricted to restricted marine platform deposits.Five sedimentary subfacies could be subdivided:the mixing tidal flat subfacies, the peritidal bank subfacies.the semi-restricted subfacies,the restricted lagoon subfacies, and the evaporate tidal flat subfacies.With the above results,and through the study on facies correlation of three well sections and facies distribution of three key reservoir formations,it is pointed out that the sedimentary environment evolution of Jialingjiang Formation from the botteom upwards is from mixing deposit. Through subtidal deposit with low energy,to supratidal evaporate deposit.This history formed a complete developing cycle from marine transgression to regression.It is quite possible that the peritidal bank subfacies with grain rock type and evaporate tidal flat subfacies with dolomite reek type could be favorable reservoir layers.