In this work, N-isopropylacrylamide (NIPAM) and acrylic acid (AA) were graft-polymerized onto hydroxyl groups of cellulose nanocrystals (CNCs) by surface-initiated single-electron transfer living radical polymerization and free radical polymerization, respectively. Modified CNCs double-grafted with PNIPAM and PAA (PNIPAM-g-CNCs-g-PAA) were obtained. The modified CNCs were characterized by FT-IR, TG, TEM, XPS, UV-Vis and particle size analyzer. FT-IR and XPS tests confirm the successful preparation of modified CNCs; TEM shows that the modified CNCs still retain the rod-like crystal shape, but the diameter becomes wider; TG shows that the thermal stability of modified CNCs is significantly improved compared with that of CNCs; lower critical solution temperature (LCST) of modified CNCs tested by UV-Vis is about 37 ℃, at this time, the volume of the nanoparticles is shrinking, and the particle size (particle size meter test) is shrinking to 68% of the original, with the increase of temperature, the time to complete the volume phase transition becomes shorter, and the temperature response is reversible; pH-response test by UV-vis shows that when pH<5, the light transmittance of the suspension decreases significantly, indicating that CNCs after grafting are easy to agglomerate under strong acid condition, while in moderate alkaline environment, the hydrophilicity is well, and the pH response is reversible. The modified CNCs with dual response of temperature and pH are expected to be applied in such fields as intelligent drug sustained-release and intelligent responsive switching membrane.