Due to the increasing public awareness of environmental issues and the shortage of resources, the focus on products made from renewable sources to fulfill the sustainable development of modern society has intensified. Natural crystalline polysaccharides have been studied for a long time and are among the most abundant renewable resources in the world. High‐performance materials have been fabricated using crystalline polysaccharides such as cellulose and chitin. For practical applications, the mechanical performance of polysaccharide‐based materials is critical. In this review, we focus on the methods for constructing high‐strength and high‐toughness crystalline polysaccharide‐based materials. This review elucidates the three approaches of aggregate structure regulation, bioinspiration and mineralization, and the use of crystalline polysaccharides as matrices for reinforcing the mechanical properties of nanocomposites.