During the nanoparticle growth, primary particles merge with one another due to sintering and condensational obliteration destructing the aggregate structure of nanoparticles. Because the property and behavior of the nanoparticles depend on the aggregate size and structure, it is crucial to understand the roles of sintering and condensational obliteration quantitatively. In this study, the relative impacts of sintering and condensational obliteration on nanoparticle structure were investigated using numerical simulations on generation of TiO2 nanoparticles at a wide range of temperature. The effect of condensational obliteration was shown to be significant at low temperature, whereas sintering was more important at high temperature. The simulation results demonstrated that both sintering and condensational obliteration must be taken into account in the model to predict the nanoparticle structure accurately.