Tributary, as an important part of the comprehensive benefit of the reservoir will affect the comprehensive benefit of the reservoir, with the large sediment deposition in its estuary. Based on the analysis of water and sediment input conditions, reservoir operation, sedimentation volume and morphology of main and branch streams in the reservoir area, this paper studies the change of sedimentation morphology of main and tributaries, and focuses on the uplift characteristics of sandbank at the entrance of tributaries. The results show that the diversion and deposition of tributaries are related to the discharge and the sediment content of inflow, and the form of sedimentation in the reservoir area. The larger the inflow of the reservoir, the smaller the flow ratio and the siltation scale of the tributary. The larger the sediment concentration in the reservoir, the larger the sediment ratio and the larger the siltation scale of a tributary.