For the middle and low head channelization hub on mountain rivers，the check high water level plus super-elevation at the upstream of the hub determines the top elevation of the upper gate on a non-overflow ship lock，which is higher than the true value. This paper analyzes the characteristics，development tasks，reservoir operation mode，and water retaining period of the middle and low head channelization hub. Through the analysis of the influence of the elevation determined under different factors on the use and construction standard of a ship lock，this paper puts forward the suitability of the reduction of the basic water level when determining the top elevation of the upper gate on the non-overflow ship lock of the middle and low head channelization hub in mountain rivers. The analysis of a project example shows that it is appropriate to adopt the corresponding water level in the flood control standard of the city near the project.