The invention provides an optimization method for a tree network topology structure based on a queuing theory and is sued for solving the optimization design problem of large-scale user node interconnection under limited resources and preset service. The method comprises the realization steps of presetting a basic tree network topology structure, a service model and a routing algorithm; establishing a queuing node model of a single basic switching module and a queuing network mode of a whole tree network; carrying out theoretical calculation and simulating calculation on the performance of the tree network topology structure; verifying the theoretical calculation accuracy and the reasonability of the queuing network model; and optimizing the tree network topology structure and parameters. According to the method, the queuing network model is established, the tree network is analyzed quantitatively, the influences of the service strength, the cache, the switching modules and the network topology structure on the network performance are taken into consideration, and the method is applicable to the establishment of the optimum tree network topology structure under preset service demands.