Abstract: The structure of polymer materials determines their properties. Studying the morphology and structure of polymer materials is crucial. The reliability of the analysis results on the dispersion and interfacial state of the internal fillers of polymer composites is closely related to the characterization methods. The liquid nitrogen brittle fractured-scanning electron microscopy and ultrathin section-transmission electron microscopy were used to characterize the section structure of layered polymer nanocomposite such as cellulose nanocrystal/reduced graphene oxide (CNC/RGO), cellulose nanocrystal/boron nitride nanosheet (CNC/BNNS), and cellulose nanocrystal/silver nanowire (CNC/AgNW), respectively. And the effect of different sample characterization methods on the microstructure analysis of materials was investigated. The results indicated that the ultrathin section-transmission electron microscopy can be used as a suitable method for researching the distribution and interface state of nanofillers, providing a guidance for the ordered-structure characterization of polymer nanocomposites.