Abstract: Micron-size spherical activated carbon(SAC) was prepared via hydrothermal carbonization-CO2 activation using carboxymethyl cellulose(CMC) as starting materials. The effects of reaction parameters including carbonization temperature,reaction time,CMC dose,activation temperature,and activation time on the morphology and porous structure of spherical carbon(SC) were evaluated. Scanning electron microscopy(SEM),Fourier transform diffuse reflectance infrared spectroscopy(FT-IR),X-ray photoelectron spectroscopy(XPS),and N2(77K) adsorption-desorption isotherm were used for characterization of the synthesized products. The results indicated that the carbon sphere precursor,which mainly containing oxygenated functional groups of —COOR and —OH,were changed after hydrothermal carbonization. Regular carbon spheres with uniform sizes and good dispersity were prepared under the optimum conditions(200 ℃,10 h,1.5 g CMC,and 40 mL H2O). After the activation of carbon sphere precursor under CO2 atmosphere at 850 ℃ for 2h,micron-size spherical activated carbon with surface area of 1005.85 m2/g and average pore diameter of 2.78 nm was obtained.