The Minjiang River is the largest river in Fujian Province,playing a pivotal role in regional economic development,flood control safety,shipping transportation,and ecological environment.Since 1998,under the dual influence of human activities and natural factors,the riverbed of the South Port has been comprehensively deepened,water levels have dropped,water flow has become unobstructed,and the diversion volume has increased sharply.While the estuary of the North Port has been silted up,with overall slight siltation,the water flow is in a state of blocked upstream and hindered downstream,and the diversion volume has decreased sharply.The pattern change of the diversion ratio between the North and South Ports,as well as the drastic changes in riverbed deepening and flow pattern,have posed severe threats to the shipping safety of ships in the North and South Ports,bridge safety,flood control,drinking water quality in Fuzhou,ecological environment,and urban landscape.This paper comprehensively uses historical data and measured data in recent years to fully analyze the laws of river regime changes and existing problems in the North and South Ports,and proposes targeted governance schemes such as dredging the large shallow ridges at the estuary of the North Port and dredging the main channel of the North Port with a length of about 5 km,and adjusting the single-hole two-way navigation of the Xia'nan bridge group in the South Port to a double-hole one-way navigation scheme.At the same time,a mathematical model is applied to preliminarily predict that the diversion volume of the North Port will be increased from the current 20% to 28%,and a ship model is used to verify the shipping safety of the new route scheme in the bridge group area of the South Port,providing reference for the comprehensive development and governance of the North and South Ports in the lower reaches of the Minjiang River.