Modern solid-propellant rocket motors (SRM) are laden with aluminum powder to increase the specific impulse. In SRM chamber, on the one hand, aluminum droplets evaporate and burn to form alumina smoke, on the other hand, the alumina smoke agglomerates to droplets as droplets collide with each other. The agglomeration model is employed to simulate the burning droplets. And breakup model also used. To avoid complex reaction theory, the article solves the mass, momentum and heat equations of disperse and continuity phases to simulate the chemic reaction. Results showed that burning efficiency and agglomeration of droplet varied by different initial diameters, and the temperature as well as smoke concentration also changed, especially in nozzle inlet.