The crosslinked chitin was prepared by the reaction of epichlorohydrin with chitin which was isolated from waste marine sources. and the crosslinked chitosan was prepared by deacetylation of the crosslinked chitin. Resin(I) was synthesized by the chlorination and phosphorylation of crosslinked chitosan using phosphorus oxychloride in dimethylformamide solvent. And Resin(Ⅱ) was prepared by the amination of Resin(I) in aqueous ammonia solution in the presence of KI. Finally, Resin(Ⅲ) was synthesized by the phosphorylation Resin(Ⅲ) with urea and phosphoric acid mixture. For these chelating polymer. the adsorption characteristics of infinitesimal amount of uranyl ion were investigated with the variation of pH, time and amount of adsorbent from fresh water, artificial seawater and natural seawater, respectively. The results were summarized as follows : with the increase of pH values, the amounts of uranium adsorbed increased and reached maximum at pH 5, but decreased at pH 6∼7 region. The adsorption of uranium by Resin(Ⅰ) reached equilibrium within 2 hours but Resin(Ⅱ) and Resin(Ⅲ) reached within 1 hour. It was observed that Resin(Ⅰ), Resin(Ⅱ) and Resin(Ⅲ) uptook uranium 3.22 μg/0.2g Resin(Ⅰ), 3.27μg/0.2g Resin(Ⅱ), 3.28μg/0.2g Resin(Ⅲ), respectively, from natural seawater. To the heavy metallic ions such as Co^2-, Cu²⁺ and Ni²⁺ ions Resin(Ⅲ) showed 100% adsorptivity in pH 2∼6 range. To Hg²⁺ ion showed adsorptivity at pH 2 but gradually decreased with increase of pH values. To Cr⁶⁺ ion Resin(Ⅲ) showed about 80% adsorptivity in pH 2∼7 range.