Due to its complexity, the fundamental mechanism of debris flow is still not fully understood. In this study, debris flow mobility and reverse segregation were investigated experimentally. A 1.4 m long flume inclining at an angle of 45° to the horizontal and a 4.4 m long flume were used to study mobility and reverse segregation, respectively. Leighton Buzzard sands (fractions C & E) (uniform sands) and completely decomposed granite (CDG, a non-uniform sandy soil) prepared at different water contents were used to simulate different debris flows in the experiments. With the use of a high-speed camera, particle trajectories in dry granular flows were captured. The mechanism of reverse segregation during the deposition process was investigated.