Chitosan is derived mainly from crab and shrimp shells. It is a linear and high-molecular substance, whose structure is similar to that of the β -1-4 type of cellulose. Chitosan can be used as a paper additive to directly improve the bond strength between fibers.In the process of papermaking, chitosan may be added either before 01 after web formation. By adding the right amount of chitosan before the formation of fiber networks, the breaking length of paper will be increased by 18.1%, the relative breaking endurance, by 14.4%, the folding endurance, by 28.6%, the wet breaking length, by 77.1%, and the drainage degree, by 14.4%.