Abstract: In order to conduct similarity experiment to utilize efficiently the results on small watershed of the loess plateau in China, a design means and experimentation technology and its verification test were carried out based on similarity theory and hydrodynamic principles of rainfall, runoff and infiltration. The experiment conditions were that normal and scale 100 is the model complying with the similarities of geometric, rainfall, flow, erosion production sediment transport and bed deformation etc. The verifying experiment results indicated that the movements of rainfall, flow, production sediment and bed deformation agreed with the practical situation in Kangjiagou small watershed of the loess plateau of China. It can be used to control soil erosion, schedule farm operations and utilize water and soil resource effectively.