The surface of activated carbon fibers (ACFs) was modified by using sodium hypochlorite in present work to improve the acidic groups on the surface and the removal efficiency of heavy metal ions in water.The adsorption time and temperatures affecting the removal rate of copper (Ⅱ) were analyzed, and results indicate that adsorption equilibrium was obtained within50 minutes and the removal rate increased with increasing temperature.It can be concluded from the fitting results of pseudo-first-order and pseudo-second-order kinetic models that the pseudosecond-order kinetic model satisfactorily correlated the experimental data, with R2 larger than0.99.Fitting results of intraparticle diffusion model show that the adsorption process was controlled by liquid film diffusion and intra-particle diffusion.In addition, the thermodynamic data suggest that the adsorption process was endothermic and could occur spontaneously.The adsorption activation energy is 20.48 kJ/mol, revealing that it belong to physics adsorption.The removal of copper (Ⅱ) ions in water using modified ACFs is significantly higher than that using ACFs, showing an increase from 70.2%to 94.5%.