We prepared spherical microcapsules modified by carboxymethyl cellulose (CMC) with urea-formalde-hyde (UF) resin as a shell material with a two-step process by in situ polymerization, and characterized the micro-cosmic features, chemical structure, and thermal perfor-mance of the microcapsules by SEM, FTIR, DSC, and TGA. We studied the effects of different experimental parameters of curing pH, the amounts of the emulsifier and emulsion speed. The CMC-UF microcapsules had good heat resistance and stability. The enthalpy of CMC-UF microcapsules reached 50.33 J g-1. Therefore, CMC-UF resin can be used as a potential wall material of phase change materials.