A method for modifying a non-woven fabric of chitosan fiber. The method includes: adding succinic anhydride to an industrial alcohol, ethanol, or acetone; controlling the mass ratio of succinic anhydride to the non-woven fabric at between 0.8 and 3.5; and stirring the resulting mixture until the succinic anhydride has dissolved to yield a succinic anhydride mixed solution; placing the succinic anhydride mixed solution in a constant temperature shaking bath; heating the succinic anhydride mixed solution; adding an HCl solution to the succinic anhydride mixed solution, and stirring evenly to yield a HCl mixed solution; immersing the non-woven fabric in the HCl mixed solution; dehydrating; immersing the non-woven fabric in ethanol or acetone; immersing the non-woven fabric in anhydrous ethanol or pure acetone; dehydrating; and air drying the non-woven fabric.