An efficient shape-stabilized phase change material (PEG/CLMS) with improved thermal properties was prepared using carbon layer-modified mesoporous silica (CLMS) as the supporter of polyethylene glycol (PEG). The CLMS was fabricated based on dopamine biomimetic modification, which is facile, environmentally friendly and easy to use. The physical properties and chemical compatibility of PEG/CLMS were studied, and the results show that after the SBA-15 was modified by carbon layer, the phase change enthalpy of PEG/CLMS-b increased from 112.0 J/g to 129.9 J/g and the thermal conductivity increased from 0.34 W/(m center dot K) to 0.43 W/(m center dot K). Moreover, the PEG/CLMS-b had favourable thermostability and thermal reliability. The carbon layer modification method reported in this paper has great potential in practical applications for thermal energy storage. The thermal property improvement method developed in this study could also be used for shape-stabilized phase change materials (ssPCMs) prepared using other carriers such as diatomite and palygorskite. Therefore, a universal method was developed to improve the thermal properties of ssPCMs in this study. [GRAPHICS] .