Many features of organisms have the possibility that can be applied to the infrastructure and network system for the communication. From the previous studies, the network system of the venation is known as the strong network on the damage. This relates the structure of leaf vein. In this study, we are focusing on the network of leaf vein to understand the strong network system. First, we study the network structure to know the relation between damage on leaf and the strong network. Then, the influence of damage on leaf vein for the water absorption on the leaf was studied with the dye flow visualization. The result shows that the network type of vein on real leaf is the mesh type network. The mesh type network has the benefit to make a bypath when the vein has the damage. The result of dye flow visualization shows that the real leaf requires the single vein to make a bypath for damage region. The increasing of area on water absorbed relates the distance of water absorption. This means that number of vein is not dominant for the speed of water absorption. Therefore, the network of leaf vein has a high robustness from the damage of vein by the mesh type network.