Abstract: Abstract The study of cationic grafting to cocoon floss with 2,3-epoxypropyl triethylammonium chloride（GTA） and the dye absorption of the modified cocoon floss that conclude three branches of reactive dyes, two branches of acid dyes and one branch of direct dye. Through the infrared spectrum of modified cocoon floss, it shows that 2,3-epoxypropyl triethylammonium chloride is mainly grafted on the amino of cocoon floss. And the particle surface potential analysis shows that the value of modified cocoon's surface potential increases from -56.2 mV to -23.2 mV. Also the dye adsorption rate of modified cocoon floss is very fast and the value of absorption is big, especially a large number of the adsorption is completed in the first few minutes. And the decolorization rates of acid and direct dyes are bigger than reactive dyes. The cationic grafting rate of modified cocoon floss is higher, the dye adsorption capacity is greater. For example, when the grafting rate of modified cocoon floss is 0.31%~2.70%, the equilibrium adsorption values of acid dyes, direct dyes and reactive dyes are 16.0%~81.3% (g/g), 31.2%~50.6% (g/g) and 5.16%~32.4% (g/g), which shows that the modified cocoon floss has a very strong ability to absorb dyes. And also, this is a potential method of the treatment of printing and dyeing wastewater.