Abstract: Although located at a straight reach of Oujiang River, the Qingtian hydroproject is faced with complex flow conditions for navigation, for there is a few unfavorable factors such as tributary upstream of the hydroproject, tide and narrowing waterway downstream of the hydroproject. Based on an integrated physical model test studies, the navigable flow conditions at the approach channel entrance area and the connection section of the shiplock of the original layout have been simulated and analyzed. The model test results show that the original layout of the hydroproject and the navigable structures are basically reasonable, however the cross current is easy to appear at the entrance area of the approach channel especially under circumstances of the median and low flow discharge, and it must result in unsafe navigation of vessel passing through the approach channel and also will affects the waterway throughput capacity of the hydroproject. Regulating the guide walls and waterway regulation line and optimizing the original layout schemes of the navigation structures, finally a series of the proposed schemes are presented to optimize the layouts of the waterways and navigation structures as well as the maximum design navigable discharge. In addition，some influences of the tributary and tide upon the navigable flow conditions are discussed，and navigation safety concerned to the proposed layout schemes and controlled discharge is demonstrated in the study.