Abstract: This paper mainly describes the working conditions of the guide wall outside the upstream approach channel of a mountainous river project,comparing with several commonly used forms of the outer guide wall of the upper approach.It proposes a structure form of buttress floating guide wall which is more applicable to the project in a middle and lower water-level river channel.However,due to the mountainous flood surging and dropping in disorder,it either makes the guide wall in such forms take huge buttress or suffer the difficulties in the removal of pontoon.This paper considers the actual layout of Caojie shiplock in the Jialing River,and raises a proposal for the pontoon to ride out the flood,which not only saves the investment,but also solves the problem of the safety through the flood.This paper focuses on the main structure of this guide wall pontoon and the theory and process of the pontoon riding out the flood.It highlights those advantages such as construction height lower than designed flood level and unmanned management in the ship in flood seasons.