To study the development and change characteristics of fuel-air explosive(FAE) cloud in the explosion dispersal process, the formation and movement state of clouds of FAE with different densities were observed by high-speed photography, the particle velocity changes of the central point on the outside surface of the fuel cylinder were calculated by numerical simulation and the changes of cloud relative concentration at 2.5 m from the explosive center were measured by photoelectric detection method.Results show that the fuel moves mainly in the form of jet prior to the formation of clouds, after what it moves mainly in the form of diffusion.The bigger the density of fuel, the bigger the cloud extended diameter at the same moment.Fuel particle velocity under the explosive dispersal condition experiences the process of first rapid increase and then slow decrease and the maximum value of the velocity is 377 m·s^-1. The change amplitude and frequency of fuel concentration show the change from big to small in the 10~80 ms, revealing that the fuel particle space distribution inside the throwing cloud has non-uniform distribution characteristics and the uniformity of fuel particle distribution can be improved effectively as the cloud movement time extends appropriately.