Disclosed is a pharmaceutical composition for treating hyperuricemia (HUA). The pharmaceutical composition includes a polysaccharide-polyamine copolymer and a pharmaceutically acceptable salt thereof as active ingredients. The polysaccharide-polyamine copolymer is formed by copolymerization of the following two parts: a selectively oxidized polysaccharide with 2,3-dialdehydo, and a polyamine with an amino functional group; the polyamine with an amino functional group and the selectively oxidized polysaccharide with 2,3-dialdehydo can form a net structure by means of covalent crosslinking, resulting in a hydrogel with an amino functional group or a granular polysaccharide-polyamine copolymer, wherein the amino functional group in the hydrogel with an amino functional group or the granular polysaccharide-polyamine copolymer can be protonated so as to form a cationic copolymer of a three-dimensional network structure having a protonated site, and the nitrogen content of the cationic copolymer and the nitrogen content of the polysaccharide-polyamine copolymer are above 12.3 wt %, and both the cationic copolymer and the polysaccharide-polyamine copolymer are water-insoluble.