Regarding the problem that the protruding mouth 1.3 km upstream of the Dongjiang Xiajijiao pivotal dam and the tip of the secondary dam on the right bank causes a backflow area at the entrance area of the upper approach channel on the downstream right side（ashore side），the lateral velocity and the backflow velocity seriously exceed the standard，we establish a normal physical model with a scale of 1:100，compare the optimization and adjustment schemes including excavating the bulge on the right bank upstream of the dam，shortening the secondary dam on the right bank of the reservoir area，optimizing the connection form between the end of the secondary dam and the mountain，and shortening the upper approach channel，and study the navigable flow condition at the entrance area of the approach channel. The results show that above measures are effective to the improvement of the navigable condition of the entrance area of the approach channel，and the recommended scheme for the arrangement of the approach channel of Xiajijiao junction shiplock is determined.