In this study, a green and efficient persimmon tannin functionalized polyacrylonitrile fiber (PAN-TETA-PT) was prepared and used to treat U(VI). The influence of pH value, adsorption temperature and time, and fiber material dosage on the adsorption U(VI) of PAN-TETA-PT fibers were investigated, and the kinetics, isotherm, and thermodynamics of fibers were analyzed. When the pH is 6, the temperature is 30°C, and the fiber dosage is 0.2 g·L−1, the adsorption rate of PAN-TETA-PT fibers to U(VI) was 96.5%, and the U(VI) adsorption capacity was 159.75 mg/g. The kinetic and isothermal studies show that the adsorption of PAN-TETA-PT fibers to U(VI) is chemisorbed and multilayer adsorption. The thermodynamic analysis reflects that the PAN-TETA-PT is spontaneously endothermic for the adsorbed U(VI).