Formation of TiO₂ film by chemical aerosol deposition(CAD) has been investigated experimental-ly and theoretically. The carrier gas Flow rate, the nozzle-to-substrate distance and the substrate temperature were chosen as major process variables and the experimental work has been carried out to find their effects on the deposition efficiency, the film thickness and its distribution. Both the deposition effeiciency and the film thickness increased with the carrier gas flow rate and the substrate temperature but decreased with the nozzle-to substrate distance. Especially at higher rate of the film deposition, the central part of the film had a concave surface like a valley. The flow and the temperature fields of the fluid phase in the region between the nozzle and the substrate were calculated numerically. The the particle trajectories and their evaporation were also simulated numerically from the equations of both particle motion and evaporation. As a result, the evaporation of the liquid particles was to occur abruptly so that the liquid-phase region had a clear boundary. The extent of the region was found to be a determining factor in the film deposition, which characterizes the chemical aerosol deposition.