Fluidized chemical vapor deposition (FCVD) technology was developed for coating SnO2 thin film on Al2O3 ultrafine particles. TEM and HREM analysis found that SnO2 films with different structures were deposited by controlling the coating temperature, reactant concentration, etc. Nanocrystalline SnO2 film was coated at 573.15 K by gas phase reaction of SnCl4 with H2O. EPMA and EDS studies indicated that the distribution of SnO2 inner and outer of the agglomerates was uniform. Nucleation and film deposition were coexisted mechanism during the FCVD coating process. The fraction of SnO2 in the composite particles increased with increasing coating temperature, SnCl4 concentration, and coating time. The mass fraction of SnO2 in the composite particles increased strongly with the ratio of P-H2O and P-SnCl4 at low mole ratio of H2O with SnCl4, but increased little under the conditions of excess H2O with respect to and PSnCl4.