Abstract: The Yangtze River Delta region is characterized by low altitude, rapid sedimentation rate, high population density, and high demographic conflict, making it one of the regions most affected by global warming and sea level rise in China. The reconversion of regional coastline changes since the Holocene is helping to understand the region's response to future sea-level rise. In this study, the lithology, radiocarbon ages, sediment grain size of the YZSW4 core, located in the incised-valley fills beneath the westernmost part of the Yangtze River Delta, were analyzed. By integrating this data with the previously published ones of drilling cores, a dataset on elevation-age-sediment facies was established, allowing us for the reconstruction of the millennium-scale coastline and sedimentary environment. Results indicate that the sedimentary environments of the Hongqiao subdelta and Huangqiao subdelta in the four stages of 11.0～9.0 ka, 9.0～7.0 ka, 7.0～4.0 ka, and 4.0～0 ka were characterized by tidal channels, estuaries, delta fronts, and delta plains, respectively. The sedimentation rates exhibited a pattern of high-low-high-low on average of 4.21 mm/a, 1.98 mm/a, 4.04 mm/a, 1.80 mm/a, respectively. The Hongqiao and Huangqiao sand bars were found to have formed simultaneously rather than in sequence, with both being tidal sands mainly formed between 7.6～4.0 ka. Since the Holocene, the accumulation of the Yangtze River Delta was controlled by the sea-level change, as well as the position and shape of the paleo-estuary. From 11.0 to 9.0 ka, there was a rapid sea level rise, leading to significant sediment deposition near the paleo-estuary. Between 9.0–7.0 ka, a strong tidal estuary developed, resulting in sediment accumulation further away from estuary area. After 7.0 ka, the sea level stabilized, and sediment began accumulating near the paleo-estuary.