Abstract: The review began with an overview of the multilayered structural features of nanocellulose. The present methods for the preparation of nanofibrillar cellulose by multilayer structural disassembly were presented, including mechanical, chemical, biological and mechanochemical methods, and the advantages and disadvantages of the various preparation methods were also discussed. Secondly, the restructuring of the hierarchical structure and functional applications of nanocellulose were also reviewed, and the regulatory role of nanocellulose in the biomineralization was mainly introduced. The strengthening effect of nanocellulose on gel materials and composite materials was presented. Recent advances in the application of emerging smart electronic devices was summarized. Finally, an outlook on the preparation pathway, structural reorganization methods and functional application prospects of nanocellulose was presented. The idea of combining it with supramolecules to construct functional supramolecular polymers was proposed. The main problems needed to be solved and the future development direction in the green and efficient preparation and functional application of nanocellulose were put forward.