Abstract: The dispersed treatment solution containing nano-TiO₂ with size distribution ranging from 30 to(60 nm) and chitosan was prepared and applied to the modification treatment of the tussah silk fiber.The structure and mechanical properties of the treated fibers were studied.The results indicated that nano-particles were dispersed homogeneously and the citric acid and maleic anhydride as cross linkers in treatment solution reacted with tussah silk and chitosan.The crystallinity of treated tussah silk fiber was increased and more β-sheet structure was formed.It was also found that the longitudinal morphology of the tussah silk fiber treated with nano-TiO₂ and chitosan solution had slight longitudinal stripe,and the mechanical properties including breaking strength,breaking elongation,initial modulus and breaking work of the treated silk filaments were increased to some extent.