In this paper, graphene oxide (GO) with full band light absorption and photo-thermal conversion property was selected as the photo-thermal conversion material. The GO/PEG composite phase change material (PCM) was prepared by ultrasound-assisted physical blending. The micro-structure, crystallinity and chemical composition of the composite PCM5 were characterized by XRD, SEM, and FT-IR analysis techniques, respectively. The thermal storage properties and photo-thermal conversion performance of GO/PEG composite PCM5 were tested by DSC and self-assembled photo-thermal conversion test system. The results showed that the inter-layer spacing of GO was enlarged. PEG was distributed between the layers and surfaces of GO through the capillary force of GO and inter-molecular hydrogen bonding. The latent heat of the GO/PEG composite PCM5 were more than 80 J/g and the phase transition temperature was 50.5 degrees C. The composite PCM could absorb visible light (300-800 nm) and store energy through light drive. Photo-thermal conversion efficiency of the GO/PEG reached 0.75, which indicated that the prepared GO/PEG composite PCMs had great application prospect in the field of photo-thermal conversion. (C) 2019 Elsevier Ltd. All rights reserved.