The microcapsules containing paraffin were prepared through the in-situ polymerization method using UF as the wall materia1. The morphology and thermal properties of the microcapsules were characterized by scanning electronic microscope(SEM)and differential scanning calorimeter(DSC), and the effects of the ratio of core to wall on the morphology and phase change properties of the microencapsulated paraffin were investigated. The results showed that when the ratio of core to wall was equal to 2:1, the phase-transforming point and the latent heat of microcapsules was near to those of paraffin core.