Plenty of particle transport and sedimentation in arid and semi-arid areas are threatening the development of photovoltaic, wind power and other industries. However, the lack of basic experimental data has severely limited the understanding of particle motion processes and subsequent disaster prevention work. We carried out the dust diffusion and settlement in mountainous area experiment in environmental wind tunnel using 100 μm, 300 μm, 500 μm and 300 μm mixed with 500 μm sand particles. The wind speed profile changes dramatically at the mountain model position and the large wind velocity gradient provide significant aerodynamic forces to the sand particles and affect their trajectories. With the increase of sand particle size, the strength and probability of collision between particles and particles are greater, resulting in a larger gap between particles and particles. Sand particles at 500 μm are more affected by gravity and form flatter trajectories. Sedimentation distributions are all single-peak curves with different particle sizes, and the larger horizontal transport flux will result in an asymmetrical distribution of sand settlement. Large particles and small particles interact with each other and the result that the sedimentation peak location is averaged.