The use of TEMPO to catalyze the oxidation of cellulose is considered an effective method. It can fully oxidize the lignocellulosic fiber structure in its suspension reaction system, and establish good basic conditions for subsequent mechanical dissociation. TEMPO is a water-soluble, stable nitrate radical. It can be used to selectively catalyze the oxidation of the primary hydroxyl group of polysaccharides to convert them to carboxyl groups. Current studies show that the 4-H-TEMPO media system catalyzes the oxidation of lignocellulose. The primary alcohol hydroxyl group at position C6 can be selectively oxidized to an aldehyde group and further oxidized to a carboxyl group. In the aqueous suspension, the selectively oxidized wood fibers by TEMPO can be broken down into single cellulose nano-chemicalbook rice filaments by gentle mechanical treatment. That is, TEMPO oxidized cellulose nanofibrils (TOCNFs). This is because the high-density carboxyl groups introduced on the surface of the fiber carry an anionic charge in water. Therefore, in water, the electrostatic repulsion between them can effectively act on cellulose nanofibrils and promote their effective dissociation. The preparation of TOCNFs by TEMPO media oxidation treatment system has unique advantages. Its reaction conditions are mild, the raw materials are cheap and easy to obtain, green and environmentally friendly, and the TOCNFs prepared have a more uniform diameter and excellent mechanical properties, which has attracted extensive attention from a large number of scholars. However, there are still some inevitable problems in the preparation process, which require the unremitting efforts of the majority of scientific research enthusiasts and staff to obtain greater research use.