CaCl2·6H2O is selected as the original substrate for research, and a new composite phase change material (CPCM) suitable for air-conditioning was developed through experiments. The new modified CaCl2·6H2O CPCM uses glycerol as a temperature regulator and barium hydroxide octahydrate as a nucleating agent. The experimental results show that when the mass ratio of CaCl2·6H2O to glycerol is 85:15, the melting temperature of the CPCM is 11.8 °C and the enthalpy of phase change is 112.86 J/g. The chemical composition of the CPCM was characterized by Fourier transform infrared spectroscopy, which confirmed that the material was successfully developed. When the amount of barium hydroxide octahydrate nucleating agent was 1.0 wt.%, the supercooling of the CPCM decreased to 1.22 °C. CPCM still show good stability after 50 thermal cycles and can be used in practical production.