Abstract: This study analyzes the samples from QDQ2 borehole of the Qidong area, Jiangsu Province, to investigate the sedimentary evolution of the Yangtze River Delta since the Late Pleistocene and its implications for the paleoenvironment. Grain size analysis was performed on the borehole sediments to reconstruct their evolutionary characteristics. The results indicate that the sediments predominantly consist of silt and clay, with fine-grained size and poor sorting. AMS¹⁴C dating suggests that the sediment at the depth of 117 m, 86 m and 40 m is approximately 40 057 cal yr B.P., 36 105 cal yr B.P. and 10 112 cal yr B.P.years old, respectively. Based on comparisons with the lithology, grain size characteristics, and dating results of other boreholes in the region, the strata of QDQ2 borehole include, from bottom to top, Upper Pleistocene strata (128.2～50.56 m) and Holocene strata (50.56～0 m). The lower part of the Upper Pleistocene (128.2～108.85 m) is primarily composed of well-sorted silt, with a unimodal grain-size frequency curve. The middle part (108.85～73.45 m) contains medium to coarse sand, exhibiting predominantly bimodal or multimodal frequency curves. The upper part (73.45～50.56 m) is dominated by silt, showing unimodal or bimodal frequency distributions, while the Holocene strata (50.56～0 m) consist mainly of silt with low sand content. The study identifies at least two significant fluctuations of regional sea-level. The first regression occurred during the early Late Pleistocene (108.85～73.45 m), followed by a rapid transgression (75～50.56 m). A subsequent regional regression took place at the latest of Late Pleistocene (LGM) (52.56～50.56 m), leading to the present geomorphic pattern. These findings provide valuable insights into the sedimentary evolution of the Yangtze River Delta since the Late Pleistocene.