Abstract: The Pinghu Formation in the western slope zone of the Xihu Sag is a key area for clastic rock oil and gas exploration. During the sedimentary period of the Pinghu Formation, this area was located in the Continental-marine Transitional Zone. Currently, there are still disputes in the academic community regarding the division of its sedimentary environment and facies types. In order to reveal the sedimentary environment and the distribution pattern of sand bodies in this area, this paper systematically analyzes the sedimentary characteristics of the Pinghu Formation by integrating data from drilling, logging, core samples, and seismic surveys. The results are as follows: ①. The Pinghu Formation has both the sedimentary characteristics of braided river deltas and tidal flats. Ten sedimentary types have been identified, including distributary channels, inter-distributary channels, subaqueous distributary channels, inter-subaqueous distributary channels, mouth bars, distal bars, prodelta mud, sand flats, sandy-muddy mixed flats, and mud flats. ② In the northwestern part of the study area, braided river deltas are mainly developed; in the central part, the deltas are affected by tides, resulting in the development of subaqueous distributary channels that have been modified by tides; in the southeastern part, tidal flats are developed. ③ In the early sedimentary stage of the Pinghu Formation, it was in a transgressive stage. In the study area, tidal action was dominant, and the modification effect of tides on the delta was enhanced, leading to a relatively large scale of tidal flats. In the later stage, it entered a regressive stage, mainly controlled by fluvial action. The influence of tides on the braided river delta was relatively small, and the delta advanced towards the southeastern part of the study area.