Light-driven carbon fiber (CF)/polyethylene glycol (PEG)/silica (SiO2) composite phase change materials (PCMs) with high thermal conductivity, and at low cost were successfully prepared through a sol-gel process. Structural and thermal property were characterized by scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) analysis, X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetry analysis (TGA), and differential thermogravimetry (DTG). The CF/PEG/SiO2 composite PCMs showed amazing fusion and crystallization enthalpies of 142.6 and 154.4 J/g at CF content of 3%, and the thermal conductivity coefficient reached 0.45 W/(m.K). The prepared PCMs also showed excellent light-thermal energy conversion capability, and a potential for wide application in improving the utilization efficiency of solar energy.