Abstract: Duliujiang river basin was selected as the research object which was seriously affected by antimony mining activities. The samples of river water and suspended particles in the main and tributaries during the wet and dry periods were collected respectively. Based on the field hydrogeology survey and experimental data, the distribution, migration and transformation of antimony (Sb) in the river was studied, and its speciation and purification mechanism were also revealed. The results showed that the Sb contents ranged from 0.00 to 86.30 μg·L^-1 in wet season and from 5.10 to 487.26 μg·L^-1 in dry season. The dillution effect was stronger in wet season. Because the Sb was mainly from the Sb₂S₃, it had a significant positive correlation with sulfate. The weak alkaline water environment in carbonate area is helpful to the oxidation and dissolution of stibnite (Sb₂S₃) in slag. The dissolved Sb has the main form of SbO^3- which has a strong mobility, and its content decreases along the flow direction and varies with the impact of polluted tributary and secondary release of reservoir sediment. The suspended particle has a purification effect on dissolved antimony. The ratio of dissolved and particulate antimony is between 28-1 180. The concentration of Sb in the exit section decrease to 5.34 μg·L^-1 in wet season and to 9.75 μg·L^-1 in dry season under the dilution of tributary and the regulation of the water control project. Therefore, the Sb content and transmission flux could be decreased through the treatment of contaminated tributaries and with the regulation effect of water control project, and prevent its ecological hazards.