Thermo-responsive textile is a widely studied smart material, which finds wide application in self-adjustment, water-storage and medicine control releasing etc. Cotton is one of the mostly researched textiles due to its low cost and easy-preparation. However, it is difficult to graft thermal responsive polymers on cotton because the hydroxyl groups on the surface are not reactive enough. In this study, a dye mediate, 2-Chloro-4,6-diamino-1,3,5-triazine (CDATA) was used to introduce amino groups onto cotton fibers. NIPAAm was then grafted onto cotton by atom transfer radical polymerization (ATRP), which was measured by infrared and contact angle measurements. The obtained cotton-PNIPAAm exhibited an efficient thermal responsive performance, which was indicated by transitions between hydrophilicity and hydrophobicity reversibly according to the temperature changes.