Phase change compound BPTCD-PEG was synthesized by esterification reaction between 3,3',4,4'-benzophenone tetracarboxylic anhydride and polyethylene glycol (Mw 2000). BPTCD-PEG had a photothermal response and it could form liquid crystal state during the phase change transition process. Under polarized optical microscope, the polymer showed a typical focal cone-shaped nematic liquid crystal texture. The thermal properties of BPTCD-PEG were characterized by differential scanning calorimeter (DSC). There was an obvious melting peak at 41.7 ℃ and a crystalline peak at 30.7 ℃, and the latent heat of phase transition was 80.42 J/g and 63.71 J/g, respectively, indicating that BPTCD-PEG had remarkable heat storage and temperature regulation performance. BPTCD-PEG was grafted onto cotton fabric to prepare cellulose liquid crystal composites with heat storage and temperature regulation properties. The surface morphology of the modified cotton fabrics was characterized and the thermal regulation properties were tested. In the temperature range of 30-40 ℃, the heating and cooling rate of the unmodified pure cotton and modified cotton with 80% BPTCD-PEG were recorded using infrared thermal imager. Compared with the unmodified pure cotton, both the heating rate and cooling rate of modified cotton fabrics with 80% BPTCD-PEG were significantly slower. The results indicated that during the heating process, BPTCD-PEG decreased the surface temperature of cotton fabrics and during the cooling process, BPTCD-PEG increased the surface temperature. It is proved that the cotton fabric treated by BPTCD-PEG has the property of heat storage and temperature regulation in this temperature range.