The synthesis of a new dihydroxyl mesocyclic diamine grafting chitosan is presented. This derivative is formed by reaction of dihydroxyl azacrown ether with expoxy-activated chitosan. The obtained copolymer contains amino functional groups in its skeleton and the secondary amine, and more polar hydroxyl groups. Elemental analysis, fourier transform infrared analysis, as well as solid-state carbon-13 nuclear magnetic resonance analysis were used to characterize chemical modifications of the chitosan. The adsorption properties of the dihydroxyl mesocyclic diamine grafted chitosan for Ag+, Pb2+, Cd2+, and Cr3+ were studied. The experimented results showed that the novel chitosan derivative has good adsorption capacity and high selectivity for Ag+ in the presence of Pb2+, Cd2+, and Cr2+, and its adsorption selectivity is better than that of chitosan. The selectivity coefficients were KAg+/Pb2+_ = 12.25, KAg+/cr3+ = 6.12, and KPb2+/cr3+ = 0.52, respectively.