The Minjiang Qianwei navigation-power junction is a vital link in the comprehensive development and construction of the Minjiang navigation-power development.As an important channel for Sichuan's large-scale transportation, Minjiang's water transportation is of great significance.In order to ensure the smooth flow of the Minjiang waterway during the construction period, especially in the second-stage cofferdam phase of the diversion during the construction period, the temporary channel is adopted for navigation, and the channel layout and route are adjusted greatly.Related parameters such as flow velocity, flow pattern and ship's navigation attitude are measured by hydraulic model test and ship model test.The results show that the original design scheme had insufficient water depth at the inlet during the dry season, and the flow pattern of the vertical cofferdam head appeared under large flow, which was extremely unfavorable to ship navigation.According to the test results, the corresponding optimization measures are proposed.After optimization, the upstream inlet is basically eliminated or improved during the low water period and the mid-flood stage cofferdam head flow pattern, making the overall flow velocity distribution in the middle of the design channel more uniform and improving navigation conditions，which provides a reference for the navigation of construction cofferdams of similar hubs.