Spur dikes,dredging,reef blasting,bank protection,and other projects are generally adopted for river channel regulation in mountainous rivers,which inevitably causes disturbance to the current water ecological environment during construction.Taking the first phase of the river channel regulation project in the lower reaches of the Minjiang River as an example,this paper conducts field monitoring of typical reaches in the whole process of construction,involving water quality,plankton,benthic animals,fish and other species,and resource quantity.It is found that the concentrations of chemical oxygen demand,five-day biochemical oxygen demand,ammonia nitrogen,total phosphorus,petroleum,and suspended matter increase after construction,but they do not exceed the limits of relevant standards.There is no significant reduction in algae,aquatic vascular plants,zooplankton,benthic animals,fish,etc.before and after the construction.Through reasonable construction avoidance in time and space,the influence of river channel regulation on the water ecological environment in mountainous rivers can be alleviated.