Abstract: According to the problem of time consuming on large-scale 3D clouds rendering in virtual environment,this paper presents a real-time simulation method for large-scale 3D clouds.In modeling process,the Navier-Stokes equations are adopted for cloud modeling,and a method based on octree is presented to reduce the particle number of the cloud model.In rendering process,impostor technique is used and a schedule algorithm based on Cell is proposed to render the mixed 3D clouds and impostor automatically.As the clouds are simulated by physical model and updated in real time when the view moves,the rendering effect is highly realistic.Compared with other works,our algorithm based on Cell schedule shows better efficiency on computation,and substantially improves the jerky phenomenon effectively.