An optically transparent prawn shell with intact original shape and substantial morphological detail was developed in this study as well as the corresponding nanocomposite film. Chitosan nanofibers could be got through deacetylated reaction following a series of simple mechanical treatments under neutral condition. Polyethersulfone (PES) resin was used as matrix to prepare chitosan-nanocomposite film during the impregnated process. FE-SEM images showed that chitosan nanofiber were highly uniform and forming interweaved network structure, with the average wide mostly less than 30 nm. Compared with pure PES, light transmission of the obtained nanocomposite was 84.5 % with only 4.2 % transmission loss. Furthermore, the addition of chitosan nanofiber significantly improved the CTE of the neat PES to 16 ppm/K from room temperature to 140 A degrees C with the fiber content was 60 wt%. Young's modulus and tensile strength of the PES resin increased from 1.3 to 3.9 GPa and 39 to 91 MPa, respectively, which was attributed by the reinforcement effect of nanostructure chitosan fibers. These unique characteristics of the chitosan/PES nanocomposite would lead to a number of potential applications in some high-tech areas and are a promising move toward the environmental protection of marine-river-waste utilization.