Model test is widely accepted and used in the field of civil engineering， mining engineering and earth sciences， etc. At present， the static terrain data are measured before and after each experiment by terrestrial laser scanning， however it is necessary to explore new technology to obtain dynamic terrain data in the course of the experiment. By taking the specified experimental tests of debris avalanche as an example， the method of 4D reconstruction based on dynamic photogrammetry was described in detail. The dynamic terrain data of the model test were obtained after the data had been processed， and then the propagation and deposit features of debris avalanche were analyzed in detail. The results show that the dynamic terrain data of the model test can be obtained accurately with the method， and the interpretation of the propagation and deposit should be relatively easy by analyzing the data of model test in detail. This is not only the new technology applied in the document of the dynamic terrain of the model test， but also causes a great change for the experimental analysis， and it deserves to be applied widely.