In order to process data collected in the debris-flow dynamics experiment quickly. Under structured light 3D vision principle, reconstruct 3D surface of debris-flow alluvial fan by using multi-line structured light active measurement. Firstly, analyze the surface characteristics of the debris-flow alluvial fan, and then reconstruct debris-flow alluvial fan successfully according to the requirements of debris-flow dynamics experiment. Experimental results show that this method, by using simple equipment, can meet the requirements of debris-flow surface measurement quickly and conveniently.