Abstract: Cross-linked shape-stabilized phase change materials (STPCM) with different gel content s were preparedwith high-density polyethylene ( HDPE) and 1∶1 blend of HDPE and low-density polyethylene (LDPE) as mat rices.The relationship between the gel content of the materials and the content of the cross-linker-dicumyl peroxide (DCP)was discussed. The stabilities of the materials were investigated by circulation experiment s. The thermal propertiesof the cross-linked STPCM were measured by DSC. The result shows that cross-linking can improve the stability ofSTPCM with the formation of the network , which will prevent the paraffin from diffusing to the out side. HDPE/LDPE blend is more suitable to encapsulate the phase change materials than HDPE. The phase change temperatureand phase change heat will not be influenced by the gel extent . The addition of porous filler , for example , diatomite , can improve the stability of the material further.