Abstract: In order to design an adsorption material with higher selectivity to U(Ⅵ) while ensuring a higher adsorption capacity, gC3N4 and ammonium dihydrogen phosphate were used as raw materials to prepare PC3N4 by thermal copolymerization. The Ag3PO4/PC3N4 composite adsorption material was prepared by insitu coprecipitation method using disodium hydrogen phosphate and silver nitrate. The results of adsorption experiments show that the adsorption capacity of Ag3PO4/PC3N4 composite adsorbent for U(Ⅵ) reaches 5246 mg/g at room temperature; the distribution coefficient to U(Ⅵ) reaches 613×103 mL/g with competing ions such as Na+, K+, Mg2+, Ca2+, Sr2+, Zn2+, Ni2+ and Co2+ in solution. XPS analysis result shows that the N and Pcontaining functional groups in the Ag3PO4/PC3N4 composite adsorption material may participate in the U(Ⅵ) adsorption process. Therefore, the Ag3PO4/PC3N4 composite adsorption material is one kind of adsorption material with higher adsorption capacity and higher U(Ⅵ) selectivity.