The construction and operation of a riverine hydro-junction significantly alter the hydrodynamic conditions of the waterway，potentially affecting navigation.Therefore，it is essential to study and evaluate the navigational flow conditions during different phases of the project.This study focuses on the river segment of Nanzhi Hydro-Junction in Ganjiang River.A two-dimensional hydrodynamic numerical model of the Nanzhi river segment is established to simulate the hydrodynamic processes during both the construction and operation phases.The objective is to analyze the impact of the hydro-junction project on navigational flow conditions in the waterway.The results show that during all phases，the flow patterns within the waterway are relatively smooth and do not pose adverse effects on navigation.Under most flow conditions，the flow conditions meet the navigational requirements.However，during the first phase of construction，under a ten-year return period condition，certain areas in the temporary waterway experience flow velocities exceeding the navigational flow speed control threshold of the Ganjiang River (2.00 m/s).These areas extend for approximately 2，000 meters，with a maximum velocity of 2.54 m/s.In contrast，during the second phase of construction and the operation phase，the flow conditions within the river segment meet navigational requirements.The research findings can provide reference for the safety and operational scheduling of navigation in Nanzhi Hydro-Junction of the Ganjiang River.