The agglomeration mechanism of SiO2, TiO2, and ZnO nanoparticles by adding coarse fluid catalytic cracking (FCC) particles is studied. The core-shell structure of agglomerates is revealed on the basis of experimental analyses. Nanoparticles can be fluidized by forming agglomerates of the core-shell structure with coarse FCC particles. The porosity of core-shell structure agglomerates and the average roundness value were found to be distinctly lower than those of pure nanoparticle agglomerates. In addition, the cohesion of the core-shell structure agglomerates is far less than that of the agglomerates formed by pure nanoparticles. Due to the smaller porosity, irregular shape, and relatively low cohesion, the fluidization behavior of core-shell structure agglomerates is better than that of pure nanoparticle agglomerates.