Abstract: The effect of cellulose nanocrystals (CNC) addition on the properties of chitosan/polyvinyl alcohol (CS-PVA) matrix was explored, and the theoretical support for the fabrication of electrospun CNC/CS-PVA composite nanofibers was further provided. Using CNC, CS and PVA as raw materials, the CNC/CS-PVA composite nanofibers with different CNC content (mass fraction) were successfully prepared by the method of electrospinning. The microstructure and properties of the composite nanofibers were analyzed by SEM, TGA and FTIR. The results show that the addition of CNC leads to increased average diameter of the CNC/CS-PVA composite nanofibers, while the composite nanofibers surface becomes rougher. The mechanical properties and thermal behavior are significantly improved. With the increase of CNC content, the Young's modulus (E) and tensile strength (σ) of CNC/CS-PVA composite nanofibers first enhance and then weaken, while the epitaxial starting temperature continues to rise. When the content of CNC is 3wt%, the mechanical properties of electrospun CNC/CS-PVA composite nanofibers have the maximum values. Compared with CS-PVA composite nanofibers, E and σ of the nanofibers with CNC incorporation increase by 43.9% and 24.8%, respectively. As CNC content is 20wt%, the electrospun CNC/CS-PVA composite nanofibers diameter distribution is not uniform, some spherical structure is observed on the surface of the single fiber, and the epitaxial initiation temperature reaches to 328.83℃. FTIR analysis showes that only physical interaction is present among CNC, CS and PVA, but no chemical reaction occurres. The stability of the electrospun CNC/CS-PVA composite nanofibers with different CNC contents gradually increases with increased acidity of the solution, while the CNC loading has little effect on it.