Abstract: The cellulolytic enzyme lignin(CEL) was separated from sweet-bamboo in Northern Vietnam by using enzymatic hydrolysis. The structure characteristics of lignin were analyzed by chemical method and spectroscopy, and compared with Bambusa textiles McClure in Southern China. The results showed that sweet-bamboo lignin was composed mainly of syringl, guaiacyl and p-hydroxylphenyl units, and the mass fractions of three units are 7.68%, 5.67% and 3.97%, respectively. Mass fraction of three units in sweet-bamboo was lower than in B.textiles. The mass fraction of functional groups had been changed after cooking, methoxyl group decreased to 12.35%, while phenolic hydroxyl group increased to 3.17% and carboxyl group also slightly increased to 5.99%. Cooking affects also the molecular weight of lignin. Raw material lignin mainly concentrated in the molecular weight of less than 4000(accounted for 50.5%). After slurrying, the molecular weight of <4 000 is decreased, and >8000 is increased.

Key words: sweet-bamboo lignin, functional group