Activated carbon fiber felts (ACFFs) have abundant micropores and excellent physical adsorption properties but have a lower adsorptivity for Cu(II). A novel reactivation process, which introduced sonication in the traditional chemical-activation process, was utilized to prepared oxygen-enriched ACFFs with high surface oxygen content, high specific surface area, and high Cu(II) adsorptivity. In addition, the sonication-assisted pickling regeneration process is researched to realize the cyclic utilization of oxygen-rich ACFFs. Ultimately, the oxygen content, specific surface area, and micropore volume of the oxygen-rich ACFFs can reach 24.21%, 2674.7 m(2).g(-1), and 0.9593 cm(3).g(-1) respectively. The Cu(II) adsorption value of oxygen-rich ACFFs can reach 35.24 mg.g(-1) which is 6.94 times that of pristine felts. Its regeneration rate can always be greater than 100% after five adsorption- regeneration cycles by the sonication-assisted pickling regeneration process.