To discuss the waterway regulation technology of the tail reach of mountainous rivers,we analyze the riverbed evolution,beach risk and sediment deposition law by taking the tail reach of Fengyi yard in Nanchong section of the Jialing River as an example,and get to know the navigation-obstructing characteristics of the reach. Adopting the river model test method,we make the regulation scheme for the dredging,damming and revetment.The test results show that the regulation effect is favorable by the implementation of the optimization scheme,which solves the navigation-obstructing problem fundamentally in the fluctuating backwater area of the tail reach of the mountainous rivers.