Abstract: Reservoirs of shallow-water delta facies are the dominant oil and gas reservoirs in the upper Sha-1 member of Shahejie formation in Chaheji structural belt of Baxian sag in Jizhong depression, Bohai Bay basin. Based on the analyses of petrological feature, sedimentary structural characteristics, grain sizes and fossils, the paper studies the sedimentary characteristics and sedimentary facies distribution of shallow-water delta systematically, summarizes the depositional model of shallow-water delta and describes the favorable accumulation conditions of shallow-water delta. The study results show that in the upper Sha-1 member, the distributary channel of shallow-water delta is well developed, river mouth bar does not occur and large-area sheet sands are extensively distributed. The cyclic variations of lake level result in sandstone interbedded with mud at multi-stages, which is the main controlling factor of sand body distribution. The sedimentary characteristics of shallow-water delta could determine that in this facies there exist pretty good reservoir-caprock assemblages and various traps are then formed due to faulting to sandbodies. The upper Sha-1 member in Chaheji structural belt has good oil and gas accumulation conditions