Effective radioactive wastewater disposal is of great significance to the wide use of nuclear energy. In this work, 4, 4ˊ-[1, 4-phenyl-bis (9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-yl) dimethyneimino)] diphenol (t-DOPO) was used to modify microcrystalline cellulose microsphere (t-DOPOR) to further enhance it affinity toward U(VI) through radiation method. The t-DOPOR were characterized for structural, morphological, and thermal properties by FTIR, SEM and TGA, which prove that t-DOPO is successfully modified on cellulose. Combination the advantage of cellulose and t-DOPO, t-DOPOR possessed abundant functional group (-OH, -NH and P=O), and exhibited extremely strong affinity toward U(VI) with a maximum adsorption capacity of 51.51 mg/g at pH 3. Particularly, A large distribution, KdU, up to 2.54×104 mL g−1 is found, implying extremely strong affinity toward U(VI) than Ln(III) (La(III), Eu(III), Dy(III), Yb(III)) at the binary system. Dynamic column experiment confirmed that t-DOPOR could separate selectively U(VI) in column experiment. In addition, even in the simulated groundwater trace amount of U(VI) was also eliminated efficiently by t-DOPOR. Lastly, the adsorption mechanism elaborated by XPS analysis was inner-sphere surface complexation between U(VI) and -OH, -NH and P=O groups of t-DOPOR. Overall, the synthesized t-DOPOR may be utilized as a promising adsorbent for separation and remediation of U(VI) from wastewater.