Abstract: Chitosan nanoparticles were prepared by the ionotropic gelation method.The aggregation structure change ofB.morisilk treated with chitosan nanoparticle dispersed solution with different mass concentrations was studied.The results show that the conformation ofB.morisilk treated by chitosan nanoparticles has the trend of-βsheet,and the crystallinity and thermodynamic stability increase.Moreover,as mass concentration increases,the trend of-βsheet strengthens and the thermodynamic stability further improves.