Cellulose is the most abundant organic macromolecule in nature and is renewable, degradable, and biocompatible. The structure of native cellulose has not yet been completely elucidated. Part of cellulose is tightly combined with lignin macromolecules through chemical bonds to form cellulose-lignin complexes (CLC). The existence of the CLC structure inhibits the complete separation of cellulose from lignocellulosic material, which not only increases the consumption of chemicals in the cooking process and causes environmental pollution, but also makes the cellulose subject to certain degradation during the deep delignification process. Therefore, elucidation of the relationship between the cellulose-lignin connection structure and performance is of great significance for efficient separation of cellulose. This article reviews the current research status of CLC and discusses the research progress regarding its biodegradation characteristics.