In order to study the influence of dam material composition on landslide dam failure process , eight groups of different dam materials are prepared for different dry density and fine particle content, and the flume model test of artificial dam is carried out to analyze the development process of phreatic line, longitudinal erosion process and collapse failure characteristics of different dam materials in the model test. The results show that: (1) The development rate of the phreatic line of the damming dam increases with the decrease of the dry density, and increases with the decrease of the fine particle content. (2)The burst duration of the dam with a smaller dry density is significantly smaller than that of the dam with a larger dry density, and the erosion rate of the dam with a smaller dry density It is obviously larger than the dam body with higher dry density; the dam body with higher fine particle content has a slower erosion rate, and the time it takes for the collapse to reach stability is longer. (3)With the decrease of dry density, the anti-erosion ability of dams is weakened, and gully is easy to form. Unstable collapse, the shorter theduration of the collapse; the greater the content of fine particles, the weaker the anti-erosion ability of the sand dam surface, the easier it is to form gully, and the more prone to multiple collapses at the breach, and the longer the duration of the collapse. The research results not only deepen the understanding of the dam disaster, but also provide a basis for further revealing the external inducing factors and the internal response mechanism of the dam.