Abstract: Natural scene simulation is always a hot issue in Computer Graphic,especially for the physically-based simulation of smoke.The subject is on the background of an actual project.This paper is based on the Stam's semi-Lagrangian scheme;MacCormack scheme is used to solve the advection item of NS(Navier-Stokes) equations,and ray casting method is chosen to render the smoke.We solve the NS equations and render smoke through the GPU(Graphic Processing Unit).This method can be taken for realistic animation and real-time simulation of smoke in three-dimensional space.