Abstract: Based on the vertical slice method, the debris flow is divided into different parts along the sliding direction. And combined with imbalanced thrust force method, the force between the initial article, initial acceleration and the initial velocity of debris flow is calculated. In the process of movement, the depth of entrainment scraping of debris flowis calculated using Voellmy model and Mohr coulomb criterion. And when the spring-block model is applied, the velocity of each sliding block is obtained at different time. Through constant iterative method, the debris flow breaks down when the velocity of each sliding block reach to zero. Therefore, the distance and depth of entrainment are calculated. In order to verify the correctness and practicability of the model, the comparison between calculation result of this article and experiment result of physical modeling test for entrainment effect of debris flow is conducted.