The invention relates to chelation group-containing chitosan and a preparation method and application thereof. The chelation group is cross-linked dithiocarbamate and ferric ion-supported amino methylene phosphate. The chitosan with various chelation groups is synthesized by using low-priced environment-friendly chitosan sold in the market as a raw material. The chelation group-containing chitosan has larger chelating capacity and higher chelating speed, and can efficiently, quickly and conveniently remove a plurality of heavy metal ions with complex modes existing in Chinese medicinal extract or electroplating effluent and other solution simultaneously. The chelation group-containing chitosan has good industrial prospect in the environmental protection industry.