In order to clarify the reasonable soil thickness of man-made tillage layer in the bare rock and gravel land remediation project, a simulation experiment of indoor soil column was conducted. The effect of soil thickness on particle migration process in bare rock and gravel soil was studied. According to the characteristics of bare rock and gravel soil reclamation project, the soil layers thickness treatments included 5 cm, 10 cm, 15 cm and 20 cm respectively. The bottom of the column was filled with the 5-cm-thick glass beads with a diameter of 10 mm. From the start of water seepage from the bottom of the soil column, the collecting test of leakage fluid was taken for 6 h. The results showed that: (1) The thicker soil had greater water retaining capacity and stronger stability. The water leakage in the four soil layers decreased with the increasing soil thickness. The water leakage rate increased at first and then reduced, ultimately, tended to be stable. (2) The migration quantity was negatively correlated with the soil thickness, showing an exponential function of y=3.19e-0.11x (R2=0.96). (3) The water leakage was often accompanied by the migration of the soil particles in the earlier stage, and the thinner the soil thickness was, the greater amount of water leakage and soil particles were. As the leakage process progressed, the quantity of soil particles migration was gradually decreased. (4) The content of silt was the highest in the migration particles, followed by the clay, and the sand content was the lowest. The migration characteristics of different soil particles varied with time. These findings provide scientific basis for the development and consolidation of bare rock gravel land.