To study the influence of the upstream hydro-junctions on the navigable discharge of the Minjiang channel，especially on the discharge in the dry season，taking Gaochang hydrological station as the base station，and Pengshan and Wutongqiao hydrological stations as reference stations，using the statistical analysis method，we analyze the characteristic flow and inter-annual variation trend of each hydrological station in the Minjiang River，which generally reflects the inter-annual variation characteristics of the average annual flow，the average flow from January to March and the guaranteed rate of 95%. After that，we analyze quantitatively the influence of the Zipingpu hydro-unction and Pubugou hydro-junction on the discharge and water level of the Minjiang channel using the three discharge series of the Gaochang hydrologic station. Finally，we put forward the suggestion of the minimum navigable discharge in the regulation design of this section. The results show that the operation of hydro-junctions in the upper reaches of the Minjiang River can increase the flow during the dry season. The average flow from January to March and the flow with the guaranteed rate of 95% of each hydrological station in the mainstream of the Minjiang River all show an increasing trend. The discharge of the Gaochang hydrological station with the guaranteed rate of 95% increases by 93 m3/s after Zipingpu cascade impoundment and increases by 265 m3/s after cascade impoundment. Under the influence of the two hydro-junctions，the discharge increases by 358 m3/s totally，and the water level with the guaranteed rate of 95% increases by 0.43 m. Pubugou hydro-junction has a more significant influence on the navigable discharge of the lower reaches of the Minjiang River.