Abstract: In recent years, the rapid expansion of industrialization and urbanization in the coastal zones of Jiangsu Province has led to the extensive discharge of polycyclic aromatic hydrocarbons into river systems flowing into the sea, significantly accelerating the degradation of estuarine and nearshore ecosystems. The concentrations of polycyclic aromatic hydrocarbons were determined in two sediment cores (sediment core 1 and sediment core 2) from the Sheyang River Estuary in Yancheng City, Jiangsu Province, China. The characteristics of vertical distributions, sources, and ecological risk level was analyzed, and explored the correlation between pollution of polycyclic aromatic hydrocarbons and human activities. These can provide essential scientific support for pollution control and environmental management in estuarine zones of coastal cities. The average total concentrations of 15 kinds polycyclic aromatic hydrocarbons in sediment core 1 and sediment core 2 were 122.21 ng/g and 141.88 ng/g, respectively. The average concentrations of seven carcinogenic polycyclic aromatic hydrocarbons were 66.68 ng/g and 72.45 ng/g, accounting for 52.77% and 47.83% of the total concentrations of polycyclic aromatic hydrocarbon load, respectively. High molecular weight polycyclic aromatic hydrocarbons dominated the composition, comprising 79.49% in sediment core 1 and 75.37% in sediment core 2. Among the 15 kinds polycyclic aromatic hydrocarbon, chrysene contributed the largest proportion, accounting for 15.00% and 13.30% in sediment core 1 and sediment core 2 respectively. The vertical distribution of the total concentrations of 15 kinds polycyclic aromatic hydrocarbons exhibited a stagewise increasing trend, which closely corresponded with historical variations in the discharge volume of the Sheyang River Sluice, regional industrial development, and the implementation of environmental policies. Source apportionment revealed that the major contributors were vehicle emissions (45.00%), combustion of coal and natural gas (43.00%), and a mixed source of petroleum leakage and biomass burning (12.00%). Ecological risk assessment indicated relatively low overall risk levels, with benzoapyrene-equivalent toxic risks below 10% in all samples. Redundancy analysis showed that the contamination of polycyclic aromatic hydrocarbons was positively correlated with indicators of industrial and transportation activities, with socioeconomic factors explaining 98.36% of the variation in the contamination of polycyclic aromatic hydrocarbons. Specifically, 3-ring polycyclic aromatic hydrocarbons were positively associated with arable land area and rural population; 4-ring polycyclic aromatic hydrocarbons correlated with urban population and total highway mileage; 5-ring polycyclic aromatic hydrocarbons and 6-ring polycyclic aromatic hydrocarbons were significantly related to the total power of agricultural machinery, and 6-ring polycyclic aromatic hydrocarbons also exhibited a strong positive correlation with urban population. These results suggest that the accumulation of high molecular weight polycyclic aromatic hydrocarbons is primarily driven by urban population growth and vehicular emissions, while agricultural activities are more closely associated with the accumulation of low molecular weight polycyclic aromatic hydrocarbons. Overall, the sedimentary record of polycyclic aromatic hydrocarbons serves as an effective proxy for reconstructing historical trends in regional transportation and agro-industrial activity intensity.