The Upper Jurassic Penglaizhen Formation in Chuanxi Depression is a set of flood-overlake deposits at low angular ground,under arid climatic condition and with lake level frequently fluctuating. Based on high-resolution sequence stratigraphy, we analyzed the sedimentary characteristics of flood-overlake deposits by integrating outcrop, core, experiments and drilling data, summarized its vertical stacking as well as horizontal distribution patterns,and the sand-body superposed patterns of flood-ouerlake were constructed. (1) Distributary channels and beach bars constitute the main facies types in the study area; (2) Distributary channels stretched vertical to the lake shoreline, while beach bars developed along the lake shoreline,with the formers constantly cutting through phases of the latters from alternating destruction and sedimentation by wave erosion and debris progradation into the lake,during development of high-frequency sequences; (3) Four types of sandbody superimposed patterns of different origins were classified, namely same time same facies autogenic type, same time different facies autogenic type, different time same facies allogenic type and different time different facies allogenic type.