Mesoporous silica SBA-15 was synthesized using fly ash as silicon source, PAA-SBA-15 adsorption material was prepared by surface modification of phosphoryl acetic acid (PAA), and XRD diffraction N2-adsorption desorption and infrared spectrometer characterization were performed on the adsorption material before and after the modification. The results showed that the highly ordered pores in the adsorbent material remained after modification. The PAA-SBA-15 adsorbent was used to adsorb rare earth ions, and it was found that the adsorption capacity for Eu3+, Gd3+, Tb3+, Nd3+, Sm3+ reached 18.6, 23.2, 21.9, 22.6, 20.2 mg/g, respectively. The influence of competing ions Ca2+, Mg2+, Al3+, Fe3+ on the adsorption of rare earths was studied, the results showed that Fe3+ reduced significantly the adsorption efficiency of rare earths. Adsorption kinetics and thermodynamics showed that the adsorption process fitted second level kinetics and Langmuir model, indicating chemical adsorption is dominated in the adsorption process.