Biomass-based activated carbonaceous fiber (ACF) was modified by nitric-acid oxidation under microwave heating (ACF-O) and then further treated by thioglycolic acid (ACF-S) to prepare carbon materials with high capability for the removal of Pb(II) ions. The physico-chemical properties of the original and modified ACF samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Zeta potential, Boehm titration, BET, Raman spectrum and X-ray photoelectron spectroscopy (XPS). It was found that modification treatments damage the pore and graphite crystalline structure of ACF, while the micropore structure is protected and extra oxygen-containing surface functional groups are grafted on its surface. The adsorption performance of the original and the modified ACF samples affected by adsorption conditions regarding to Pb(II) ion strength (10mg/L- 105mg/L), contact time (10min-120 min), pH value (2.5-6.5), and solvent temperature (15 °C-45 °C) was investigated through batch experiments. Compared to the maximum Pb(II) ion adsorption capacity of 75.24mg/g by ACF sample, the value was substantially improved by the integrated modification method (193.42mg/g for ACF-O and 209.21mg/g for ACF-S sample). The Biot number determined from the homogeneous surface diffusion model (HSDM) was between 1 and 100 for the original and modified ACF samples, suggesting that the adsorption process of Pb(II) ions is limited by both the surface diffusion and film mass transfer.