To work out the value of the minimum navigable water level from Badaogou to Yunfeng dam，we analyze the lowest navigable water level of this section by a combination of the observation data analysis and mathematical model，and obtain the lowest navigable water level within the region of more than 180 km，which can be used for the following-up navigable route research of this river section. This research method may serve as a reference for the research on the minimum navigable water level in the hub’s upstream and natural waterway which is lack of data.