Abstract: The auto-hydrolysate of eucalyptus prior to pulping proved that the hydrolysate was of biomass resources, rich in xylose and xylooligosaccharide.In order to get high value-added product and meet with the engineering operability, experimental results showed that the selected powder activated carbon (AC7) adsorption (with 1000r/min magnetic stirring for 10min) combined with PAANa (10²0mg /kg) flocculation could reach high decoloriztion ratio (above 95%) with good sugar retention.Besides, the furfural and lignin removal ratio reached almost 100% and 76.5% separately.Combined with IC, SEM, FT-IR, GC-MS and ICP-AES analysis of the hydrolysate and pigment in sediment, it proved that lignin and its degradation products greatly contributed to coloring, the heavy mental in hydrolysate after decoloriztion at low level.