Cellulose aerogels were prepared by combining the NaOH/thiourea/H2O solvent system and the freeze-drying technology. Hydrophobic aerogels were obtained with the cold plasma modification technology. The results showed that cellulose aerogel had good heat insulation performance, while the main factors affecting thermal conductivity were density and porosity. Thermal conductivity decreased with the decrease of density and the increase of porosity. It could be as low as 0.029 W/(m K). Cellulose aerogel adsorbed moisture easily. The moisture adsorption had a significant influence on the heat insulation performance of aerogel. After conducting hydrophobic modification using CCl4 as plasma, cellulose aerogel was changed from hydrophilic to hydrophobic and water contact angle was as high as 102 degrees. Hydrophobic modification did not affect the heat insulation performance of aerogel. This work provided a foundation for the possibility of applying cellulose aerogels in the insulating material field. (c) 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3652-3658, 2013