Given in this paper is successful experience in improvement of navigation channels in Pearl River, the largest river in South China. The reach to be improved is in the confluence zone of the West and the North Rivers. Various types of shoal exist in this waterway as a main stem for flood to progress. The flow condition is very complicated and improvement is very difficult. In this paper, based on a great deal of hydrological data and topographical data, analysis of hydro-dynamic conditions, water/sediment conditions and river bed evolution are pressented. In combination with scale modeling test, the mechanism for the shoals to grow is revealed and an improvement plan is drawn out according to the features of the waterway. According to the plan, in order to solve the deposition problem in Laoyazhou Shoal, groynes are built to move the flow diversion point and remove the circular flow on the shoal. The condition for deposition to occur is then destroyed and the shoal vanishes after improvement. The navigation channel becomes smooth. For the problems of “risk” and “shallow” at the west mouth of Sixianjiao Navigation Channel, low “lock-dams” are built in the branch to confine the hydrodynamics so as to get rid of the “risk”. At the same time, the flow overflows the dams and scours the bed materials so that the problem of “shallow” can be relaxed. After the improvement, the depth of the overall waterway increases from less than 2.0 m to larger than 2.5m. Ships over one thousand tons can then pass through the navigation channel and favorite conditions are then developed for flood disposal and drainage. Remarkable economic and social benefits are got.