The reach below Longxikou junction in the trunk stream of Minjiang River is a natural waterway，which has typical mountain river characteristics and is extremely complex in navigation obstruction.In addition,the waterway has been seriously deteriorated due to the influence of sand excavation and stone quarrying over the years.The two-dimensional flow mathematical model of long river is used to analyze and optimize the regulation scheme of 11 rapids in the proposed Longxikou junction of Minjiang River to Minjiang River Bridge section at Pingshan Town.Based on the analysis of the characteristics of navigation obstruction and the causes of rapids,three typical rapids,Ganlongzi rapid,Baijia rapid and Xinkai River rapid,are selected.The comparison and selection of several schemes are carried out from the aspects of the improvement of navigation flow,the stability of trenching and the self navigation of ships on the beach,and the regulation technology of typical representative rapids in the lower section of Minjiang River is summarized.