To improve the thermal conductivity and thermal stability of the phase change materials (PCMs), a series of novel polymeric solid-solid PCMs (SSPCMs) were successfully designed and synthesized with lamellar structures by using poly(ethylene glycol) (PEG) as the phase change ingredient, 4,4'-diphenylmethan diisocyanate (MDI) as the cross-linking agent, and graphene oxide (GO) as the skeleton material. In the preparation, GO nanosheets were introduced into the molecular structure of the SSPCMs through both self-assembly and grafted polymerization to enhance the thermal conductivity and comprehensive thermal properties. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) images reveal that the SSPCMs possess a novel, regular, lamellar structure consisting of GO sheets with an interconnected network structure, with PEG homogeneously intercalated into the sheets. This molecular structure supplies the SSPCMs with excellent phase change behavior, good thermal cycling stability, and high thermal conductivity. As a result, the SSPCMs display a fast thermal-response rate and outstanding thermal regulating performance, which can maintain their temperature in the range of 50 degrees C-57 degrees C for roughly 410 s. Herein, the novel SSPCMs provide a promising potential for applications in thermal management and thermal energy storage systems.