Fluidization behaviors Of SiO2 and TiO2 nano-particles by adding coarse particles of FCC, ordinary Al2O3 and heat-resistant Al2O3, has been investigated experimentally. The effect of size and inventory of coarse components on the fluidization behavior of nano-particles has been studied. The results reveal that the fluidization quality of the mixture systems can be improved with increasing the amount of the coarse particles. For SiO2 nano-particles, the optimum of FCC, ordinary Al2O3 and heat-resistant Al2O3 are 30%, 40% and 50%, respectively. Similarly, the optimal amount of FCC, ordinary Al2O3 and heat-resistant Al2O3 is about 30% for TiO2 nano-particles. Fluidization quality is almost the best for all these three coarse additives of 65-80 mu m. The analysis performed from the standpoint of the Richardson-Zaki (R-Z) equation reveals that the apparent terminal velocity derived through scaling experimental data to R-Z equation affects the expansion index of the mixture systems. (C) 2009 The Society of Powder Technology Japan. Published by Elsevier BV and The Society of Powder Technology Japan. All rights reserved.