According to the flow feature of the upstream approach channel of the second-line shiplock in Dayuandu junction,we explore the influence of the three main factors including the navigable flow condition at the upstream entrance area of Dayuandu junction,the discharge capacity near the sluice gate lock holes and the length of braking area in the approach channel on the arrangement of the navigable wall at the upstream approach channel using the overall hydraulic model experiment and ship model experiment,in which,the adaptability of arrangements of three lengths are compared and the conclusion is drawn that proposal of 130 m navigable wall has the best flow condition at upstream entrance area and meets the requirements of the length of braking area;the proposal of 300 m navigable wall has the least influence by the circulating flow area and the best discharge capacity of the sluice.Considering comprehensively the code stipulations and requirement of the length of the braking area,and to maximize the discharge capacity of the sluice,we choose the proposal of 130 m navigable wall as the recommended one.