Abstract: Based on the investigation of the dispersion process of fuel-air-explosives (FAE), the expansion range of the detonation products after the central explosive-tube detonated was calculated by using a two-stage isentropic expansion theory. A simplified two-phase flow model for describing the dispersion process of solid fuel grains was proposed, and the method for determining the dispersion distance is given. The results show that the sizes and shapes of solid fuel grains affect not only the dispersion distance but also the distribution uniformity of the fuel cloud. Computation results are in good agreement with the experimental observation results. The prediction method given in this paper has a satisfactory reliability.