TiO₂-doped polymethacrylate N, N-dimethylaminoethyl methacrylate (DMAEMA) (TiO₂-g-PDMAEMA) was successfully synthesized by the co-radiation grafting method with titanium dioxide (TiO₂) and DMAEMA as the base and the monomer, respectively. Meanwhile, the effects of monomer concentration and absorbed dose on the adsorption of heavy metal ion were investigated. A series of characterizations, including X-ray diffraction, scanning electron microscopy, Fourier-transform infrared spectroscopy, thermogravimetry, X-ray photoelectron spectroscopy and contact angle, confirmed that DMAEMA monomer was successfully grafted onto TiO₂ surface by electron beam co-radiation grafting method. When the absorbed dose was 60 kGy and the monomer concentration was 20%, TiO₂-g-PDMAEMA exhibited excellent adsorption capacity for Cr (VI, 10 mg/L), up to 10.75 mg/g. In addition, the TiO₂-g-PDMAEMA prepared at 60 kGy absorption dose and 10% monomer concentration displayed the optimal adsorption-photocatalytic reduction ability under visible-light irradiation, and the removal rate of Cr (VI, 10 mg/L) reached 85.56%. In conclusion, the adsorption-photocatalytic synergistic effect of this new photocatalyst could meet the requirement of removing Cr (VI) from water.