In this article, we represented the review of literature data about the study of lignin as one of the most abundant biopolymers. The review is based on the articles published in the most quoted world publishing. It is noted that already nowadays the lignin is considered as a powerful renewable source of valuable organic raw materials, also it’s pointed that potential possibilities of lignin valorization are much wider than those are used in present times. The special attention is paid to the structure and molecular organization of birch lignin, which wood is actively utilized in chemical industry, meanwhile the hardwood lignins are less studied in literature than softwood lignins. The authors touched the most basic methods of research of such complex and irregular polymer as lignin, methods’ advantages, disadvantages and perspectives are analyzed. It is noted that nowadays the most effective methods of lignin structure units study are pyrolisys gas chromatography and nuclear magnetic resonance. The article describes various ways of lignins isolation from the wood, and influence of the isolation way on the structure of isolated substance. Also, the structural features of birch lignin and its differences from other species are shown.