Abstract: Glycidyl methacrylate was grafted onto the surface of PA66 fiber using radiation-grafting method. Then, the ring-opening reaction between epoxy groups and N-acetyl-L-cysteine was carried out to prepare the amino acid modified PA66 functional fiber adsorbent. The chemical structures and surface morphologies of the pristine and graft-modified PA66 fibers were characterized by Fourier transformed infrared spectroscopy, thermogravimetric analysis,X-ray photoelectron spectroscopy and scanning electron microscopy, respectively. The effects of initial pH, initial uranium concentration and contact time on uranium adsorption performance of fiber adsorbent were investigated. The results show that the pH value of solution adjusted to 8 is conducive to the adsorption of uranium; the adsorption equilibrium reaches within 100 min; the uranyl ion adsorption process is in accordance with the pseudo-second-order kinetics model and the Langmuir isotherm adsorption model. The uranium adsorption capacity reaches 75.53 mg/g when the initial uranium mass concentration is 25 mg/L. Additionally, the fibers exhibits good adsorption selectivity for uranium in aqueous solution containing other metal ions.