<p>Phase change materials (PCMs) represent a pivotal strategy for advancing energy recycling and sustainable development. Nevertheless, practical applications of PCMs are constrained by leakage risks, high rigidity, and low flexibility, which collectively limit their broader applicability. Therefore, developing PCMs with excellent thermal storage capacity and high flexibility is essential. In this study, a flexible crosslinked waterborne polyurethane-acrylate phase change composite was successfully prepared by selecting polyethylene glycol (PEG) as the soft segment material and trimethylolpropane (TMP) and hydroxyethyl acrylate (HEMA) as the modifiers. The impact of the molecular weight and incorporation quantity of PEG and the TMP concentration on the phase change characteristics and microstructure of the flexible phase change material was examined through the utilization of analytical techniques, including Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). The experimental results demonstrate that the prepared flexible aqueous polyurethane-acrylate phase change materials exhibit good thermal storage capacity (the enthalpy of phase change is 125.6 J/g, along with favorable thermal stability and flexibility, which presents a potential for their utilization in the domains of energy storage and temperature regulation.</p>