Abstract: The decolorization results of furfural wastewater by activated carbon prepared by furfural residues through pyrolysis activated by water vapor were investigated. The results indicated that the optimal decolorization temperature of furfural wastewater was 50 ℃ by the activated carbon. The decolorization process finished quickly; the color of the liquor stabilized after the activated carbon and the liquor were fixed and stirred for 15 min. Due to the low cost of applying furfural residues to prepare activated carbon, we can increase the dosage of the activated carbon so as to improve the decolorization effect. The decolorization percent of furfural wastewater reached 86.65% under the conditions temperature 50 ℃, dose of activated carbon of 10 g/L, and stirring for 10 min. The furfural wastewater which was decolorized by activated carbon was transparent and colorless. The detecting experiment indicated that the absorbance of decolorized furfural wastewater was the same as tap water. This clearly indicated that the decolorization of furfural wastewater by activated carbon which was prepared by furfural residue was excellent.