Abstract: Dendritic polymer heavy metal precipitant with double functions of chelation and self-flocculation and its application is provided. The heavy metal precipitant is dithiocarbamates end group polyamidoamine dendritic polymer prepared by reaction of carbon bisulfide and polyamidoamine dendritic polymer with a generation at a range of 1-3 (denoted as PAMAM-(NH2)8G, wherein G is generation number). Due to the special three dimensional spatial structure, appropriate molecular weight, high density of the end chelating group dithiocarbamates, the dithiocarbamates end group polyamidoamine dendritic polymer of the present invention not only has strong chelating performance with the heavy metal iron, the sediment floc formed has a large volume, a fast sedimentation velocity and easy separation. The present invention has high efficiency performance in chelating and flocculating heavy metals.