Abstarct: one of the most important and widely used engineering structures built to stop or change the flow of water on rivers. In this research, the characteristics of the flow passing through the multi-laxyer foundation of a dam were investigated numerically. Three types of soil with 0.2, 0.6 and 1.2 mm grain size were considered for the foundation. The parameters of compressive potential and leakage flow were extracted by considering different arrangements of single-laxyer, two-laxyer and three-laxyer with the help of numerical control volume method and by coding in MATLAB software. The results showed that for the single-laxyer arrangement, with the increase of the upstream head from 370 and 450 mm, the potential value also increased. In two-laxyer and three-laxyer foundations with different arrangements, as the downstream head increased, the probability of piping increased. By examining different arrangements, the percentage of potential reduction for the arrangement of 0.2-1.2 mm was about 85.2% and for the arrangement of 0.2-0.6-2.1 mm, it was about 83.47%. For single-laxyer with 0.2 mm granulation and a constant downstream head, the output flow increased with an increase in the upstream head. For granulation of 0.2 mm, the range of changes is less and the probability of piping reduced. With the increase of the downstream head in the two-laxyer foundations, the range of output flow changes is less, and the decrease of the downstream head has the opposite result. For the downstream head of 350 mm, the lowest flow range was 0.6-0.2 mm, and due to the greater contact surface of the incoming flow with the higher and coarser laxyer (0.6 mm), the flow rate increased. For three-laxyer foundations, the best performance was related to the arrangement of 1.2-0.2-0.6 mm and the worst performance was related to the arrangement of 0.2-1.2-0.6 mm. In three-laxyer foundations, when the coarser soil is closer to the floor, the better and safer it is in performance. An increase in the downstream head led to a decrease in the flow rate and a decrease in the downstream head led to an increase in the flow rate.