The spray drying with pneumatic nozzle was simulated by using Fluent based on gas/liquid two-phase fluid theory. Contours of hot air temperature, velocity and humidity as well as residence time and water content distribution of particles in the spray dryer were analyzed by comparing with changes of the droplet in and out. The results show that the rate of droplet injection into the column is not enough to prevent the formation of viscosity-wall phenomenon. In order to improve the quality of powder products and drying efficiency, the drying time should be properly prolonged. This paper provides a solution to practical problems and a reference for designing and manufacturing spray drying tower.