Influence of unsteady flow on navigation condition of downstream channel is the main issues to consider in the implementation of Xiangjiaba project. Effects of water flow conditions and boundary conditions on the ship navigation and the interaction between the ship and the channel cannot be fully and accurately reflected in traditional study on the influence of navigation conditions.Using measurement and control technology of small scale ship model,based on similar analysis and maneuverability calibration of real ship,we research the influence of unsteady flow on navigation condition of downstream channel.Combined with experimental results,the main influence factors are quantitatively analyzed,which provide scientific and reliable data basis for the optimization design of the Xiangjiaba project.