纤维二糖（英语：Cellobiose）是由两分子β-D-葡萄糖通过β（1→4）糖苷键连接而形成的二糖，纤维二糖是纤维素这种多糖的基本重复单位。

果聚糖： 菊粉 · 果聚糖β2→6

甘露聚糖

半乳聚糖

Cellobiose is a disaccharide with the formula [HOCH₂CHO(CHOH)₃]₂O. Cellobiose, a reducing sugar, consists of two β-glucose molecules linked by a β(1→4) bond. It can be hydrolyzed to glucose enzymatically or with acid. Cellobiose has eight free alcohol (OH) groups, one acetal linkage and one hemiacetal linkage, which give rise to strong inter- and intramolecular hydrogen bonds. It can be obtained by enzymatic or acidic hydrolysis of cellulose and cellulose rich materials such as cotton, jute, or paper.