The functionalized rice straw with polyamidoamine(PAMAM) was prepared with epichlorohydrin as crosslinking agent, and its structure was characterized and analyzed by FTIR, SEM, XRD and TG. The adsorption properties of the functionalized rice straw for Nd3+, Sm3+and La3+ were researched. Physicochemical factors such as adsorption time, initial rare earth metal ions concentration, adsorption temperature, and pH affecting magnitude of rare earth metal ions adsorption were researched. At the same time, the kinetics behavior, adsorption isotherm, and thermodynamics parameters of the adsorption process were further investigated. The results showed that the adsorption equilibrium time was about 4 h for Nd3+, Sm3+ and La3+. And adsorption capacity of Nd3+, Sm3+and La3+ were 47.14, 40.11 and 50.12 mg/g, respectively. At the same time, the adsorption process fit the pseudo-second-order kinetic model and Freundlich isotherm, which indicate that the adsorption process is chemical adsorption process. In additional, thermodynamic data of the adsorption process shows that the adsorption process is spontaneous. And the randomness is increased at the solid-solution interface during adsorption process.