Laomukong navigation-power junction ranks the first among the four recently developed navigation-power junctions in the 162 km reach from Leshan to Yibin in the downstream Minjiang River.The navigation conditions during the construction period will directly affect the transportation of large ships in the reach.To ensure smooth shipping in Minjiang River during the construction period，the temporary open channel expanded at the left bank is available for navigation during construction period I.This paper adopts the method of combining hydraulic physical model tests with ship model tests to systematically study the navigation schemes and flow conditions in the dam area during the navigation period of the left branch of Sanjiang Village in the first dry season during construction period I.The paper also proposes the recommended schemes of expanding the open channel in the left bank for dredging，designing the inlet reach of the open channel，and arranging the downstream outlet of the open channel and connecting reach，as well as corresponding characteristic parameters of the navigation flow conditions.The results show that the recommended schemes for the dam area of Laomukong junction during the construction period ensure excellent navigation flow conditions，and the minimum and maximum navigation flows meet the navigation requirements during the construction period.