Aquatic vegetation is an important indicator of river health, and it is important to carry out dynamic monitoring of river aquatic vegetation. However, both traditional field surveys and satellite remote sensing have obvious limitations in monitoring river aquatic vegetation. In this study, a UAV (Unmanned Aerial Vehicle)-borne high-pixel Aerospace Shuwei KP-6 multispectral camera was used to acquire multispectral images of the Baigou River in Gu'an County, Hebei Province. Aquatic vegetation species such as reed, Nymphoides Peltata, and Ceratophyllum demersum L. were classified in the Baigou River based on three kinds of supervised classifications, and the maximum-likelihood method was examined to have the highest precision, with an overall precision of 92.8% and the Kappa coefficient of 0.91. In addition, the high-pixel Aerospace Shuwei KP-6 camera was compared with a variety of high-resolution satellites and a number of UAV-borne multispectral cameras, and was found to have the advantages of high spatial resolution, wide coverage and flexible acquisition in river aquatic vegetation monitoring. The present study can provide a useful reference for the application of UAV-borne multispectral remote sensing in riverine aquatic vegetation monitoring.