Abstract: Using N-methylol acrylamide (N-MA) and polyethylene glycol (PEG) eutectic as raw materials, poly-N-methylol acrylamide (PN-MA)/PEG semi-interpenetrating network was prepared by emulsion polymerization (SIPN) composite phase change material (CPCM). The structure and performance of (PN-MA)/PEG CPCM were characterized using FTIR, XRD, differential scanning calorimeter (DSC), SEM, EDS and other methods. The results show that the crystallization enthalpy and melting enthalpy of the obtained CPCM reach 78.38 J/g and 82.31 J/g, and the crystallization temperature and melting temperature are 36.88°C and 32.05°C respectively; the interaction between PN-MA and PEG in CPCM is physical link, no other chemical reaction occurs; the obtained CPCM is spherical and the size is relatively uniform. The small spheres with a diameter of about 200 nm are aggregated to form large spheres with a diameter of 10 μm to 15 μm. The sphere presents a dense three-dimensional net cage structure; PEG is well supported under the constraints of the cross-linked PN-MA network, and still has good crystallization performance.