Microcapsules with urea-formaldehyde shell containing canola oil are fabricated by in-situ polymerization method, which is considered as a common preparation process of the microcapsules with core–shell structure. The results suggest that the microcapsules with up to 80% yield is achieved through a suitable emulsifier concentration and agitation rate; in particular, lots of UF polymer microparticles are formed from the UF reaction, and that at the surface of microcapsules forms UF shell. These polymer microparticles are precipitated through the fine powder formation, which are bonded to the surface of microcapsules. The characterization and morphology of the microcapsules are also determined by Fourier-transform infrared spectroscopy, gas chromatograph, thermogravimetric analysis, and optical microscope. Besides, the thermal stability of microcapsules is up to 257 °C with a rough outer surface, and which have been encapsulated 76% canola oil (wt.) with 1.5 μm of thickness shell; in particular, herein the shell thickness of microcapsules is determined through the densities of both core and shell materials, the capsule radius and the content of core material. Moreover, the stability of microcapsules is maintained well within 50 days at room temperature via the extraction method. It indicates that this study opens an approach for preparing the microcapsules are employed as healing agents.