With the continuous development of the water transportation industry,low-grade channels are gradually upgraded,and in recent years,large-scale ships has developed rapidly,and the main dimensions of actual navigable ships often exceed the channel design standards.The navigation clearance scale of some bridges is not compatible with the navigation standard of the upgraded channel.However,due to the limitation of engineering investment and other reasons,it is impossible to dismantle and rebuild in time,which has certain restrictions on the navigation of the channel.This article takes the Wuxuan Bridge as an example to analyze the navigation clearance scale of the bridge,the hydrological conditions of the river section where it is located,and the navigation ship type.Numerical simulation methods are used to simulate and analyze the navigation flow conditions and collision resistance performance of the bridge.From the perspective of navigable clear width,navigation clearance height,bridge anti-collision ability and meteorological factors ,etc.,the limiting conditions and safety guarantee measures for the safe passage of various types of ships through old bridges are proposed,which can provide reference for the navigation and management of similar old bridges.