The sluice gates of the Baishiyao Hydro-Junction in the Beijiang River were selected to study the influence of the sluice gate opening mode on flow features and navigation flow conditions in the entrance area of an approaching channel downstream of the hydro-junction. Three-dimensional(3D)numerical simulation was conducted on the influence of different sluice gate opening modes on the navigation flow conditions in the entrance area of the downstream approaching channel. The results show that the influence of sluice gate opening modes on the navigation conditions is small when the flow is low, and the influence of sluice gate opening modes on the navigation conditions is large when the flow is high. For the sluice gates of the Baishiyao Hydro-Junction, a single opening of the left sluice gate or intensive opening of the left sluice gate with opening at intervals of the right sluice gate will prevent the navigation flow conditions of the right side of the first-line ship lock from meeting the requirements in the entrance area of the downstream approaching channel. To ensure the safety of navigation, it is suggested that the right sluice gate of the Baishiyao Hydro-Junction be opened or else all the sluice gates be opened during flood drainage.