Abstract: Based on percolation theory and hydrodynamics, FLUENT is utilized to simulate seepage characteristics of fire preventing and extinguishing tri-state materials in goaf and comparatively analyze the seepage ways in different velocity, different injection ways. The simulation results demonstrate that fire preventing and extinguishing tri-state materials have a low velocity in goaf with radial pattern seepage way; the optimal injection rate is 0.4 to 0.5 m/s, and the optimal injection pattern is the three nozzle injection. Because tri-state materials have an accumulation characteristic, therefore, the problems that liquid state materials and two-phase materials can be influenced by the topography and are unable to guard against upper fire can be settled effectively.