Industrial and mining enterprises are key sources of heavy metal discharges, making it crucial to systematically study the characteristics and risks of heavy metal pollution in the sediments of surrounding ditches. This study investigated and monitored heavy metal concentrations in the ditch sediments, water, and adjacent cultivated soil around a typical chemical enterprise involved in heavy metal emissions. The characteristics and ecological risks of heavy metals in the ditch sediments were analyzed, and the influence and extent of heavy metal pollution on ditch water and surrounding cultivated soil were evaluated. The results showed that the main heavy metal pollutant was Cd, with average concentrations of 16.61 mg/kg in sediments, 5.20 μg/L in water, and 1.22 mg/kg in cultivated soil. The average Cd content in sediments and cultivated soils was approximately 195 and 14 times the background value for soil in Hunan Province, respectively. The Cd concentrations in the sediments and water decreased linearly along the flow direction, with a correlation coefficient of 0.84 between the two media. Additionally, Cd levels were higher in the downstream cultivated soils irrigated by the ditch, indicating that the polluted sediments were the primary source of heavy metals in the water and cultivated soil. Risk assessments revealed that Cd in the sediments posed a high cumulative risk and severe potential risk. Due to the influence of heavy metals in the sediments, the water was presented with serious pollution risks of Cd and Hg, while the cultivated soil was moderately polluted with Cd and slightly polluted with Hg and Pb. The heavy metal pollution in the ditch sediments and water primarily affected cultivated land at altitudes lower than 46 meters around and downstream of the ditch, covering an area of about 569 hectares. This study provides a theoretical basis for source prevention and control, and targeted remediation of heavy metal-contaminated cultivated soil around industrial and mining enterprises.