Abstract: Bamboo sawdust was soaked in phosphoric acid for 48-72h and bamboo char was obtained by pyrolysis of the soaked sawdust at 200℃ for 2h. The latter was treated at 100℃ for 2h in fuming sulfuric acid to produce sulfonated bamboo char. The results of XRD and FTIR showed that the product a solid amorphous material with polycyclic aromatic rings and acidic functional groups. The result of pyridine adsorption DRIFT showed that the surface acid sites were proton type. The amount of acid in sulfonated bamboo char was 2.02mmol · g^-1 as determined by ion exchange and titration. Sulfonated bamboo char had a good catalytic activity and can be reused in the acetalization of ethylene glycol with different aldehydes or ketones.