A large number of tidal deposits are developed in the Pinghu Formation in Xihu Sag of the East China Sea Shelf Basin, which has great potential for oil and gas exploration. In this paper, core and logging data are used to analyze the lithofacies and sedimentary microfacies of Pinghu Formation in W well block of Xihu Sag, and comparative sedimentology study is conducted through modern sedimentary investigation in Rudong-Dongtai coastal area in Southeast Jiangsu Province, then the tidal sedimentary characteristics and development law of Pinghu Formation in the study area are clarified, and the sedimentary model is established. The results show that a set of tidal-controlled delta tidal flat depositional systems are developed in the Pinghu Formation in the study area, and the sedimentary subfacies mainly include delta front, supra-tidal zone and intertidal zone. Nine types of sedimentary microfacies, including underwater distributary channel, interdistributary bay, estuary bar, sheet sand, swamp, mud flat, sand flat, mixed flat, and tidal channel are further identified. Based on the analysis of the sedimentary system, a tidal delta-tidal flat sedimentary model in the study area is established, which provides reference and guidance for tidal sand body prediction and oil and gas exploration of Pinghu Formation.