Abstract: This article reviews the theoretical-graph approach towards transport and logistic systems, which allows describing key details and processes that take place therein. The question of searching for an effective solution of transport and logistics tasks and dependence of such solutions to throughput of the system and the value of the seepage coefficient. This article offers to use seepage theory as an applied instrument for describing and solving transport and logistics tasks. The indicated approach is innovative and original, which may be very promising in the context of global transport planning and management. The essence of this method, based on adaptation of seepage theory for solution of the typical transport and logistics tasks, is reduced to operation of surface run-off and origin on the graph. The model for assessment of the global throughput of transport and logistics system is developed on the basis of the methods of seepage and multidrain flow models. The author offers a model calculation of the impact of holdups upon transport and logistics systems and the tasks solved thereof. A theoretical-graph model, which reflects the structure of transport and logistics system, describes the objects and processes common to transport and logistics tasks. The toolset of graph theory allows solving the specific transport and logistics tasks, as well examining the structural properties of the system, building predictive models, as well as developing new approaches towards solving of these tasks. The characteristics of graph are correlated with the actual network, system and task, as well as with the characteristics of transport or logistics flows examined for the purpose of optimization of topological structure of the system and solution of other tasks.