Spray drying tower is a completely enclosed facilities， it is difficult to sampling analysis during the drying process. Oil-in-water （O/W） emulsions with gum arabic as wall material were prepared in this experiment. Single droplet drying （SDD） was been proposed that can simulate the environment of spray-drying， to studying the effects of the air velocities and the solids content in the emulsion on the surface formation mechanism of the particles by analysing morphological shrinkage and drying kinetics parameters of droplet during drying process. The results show that the drying behavior of droplets varies greatly at three air velocities of 0.70， 0.90， 1.10 m/s. When air velocities was 1.10 m/s， the moisture of droplet evaporates fastest， crust form earliest， the produced particles have smaller shrink rate. The total solids content of the emulsion also has an obvious effect on the drying behavior of the droplets. With the increase of the solid content， the water evaporation of the emulsion droplets decelerate， the crust form earlier， and the morphology of the resulting particle was larger. The experimental has guiding significance for studying the drying dynamic model and improvement spray drying product quality.