The invention discloses a machine vision tidal bore flow velocity measurement method based on an unmanned aerial vehicle. The method is implemented by the following six links in sequence: video image acquisition, graying and filtering processing, edge detection, puffing operation, tidal head line extraction and tidal bore velocity calculation. A traditional fixed detection method can only obtain hydrological data of limited point locations, and for the research of the overall form and the propagation mechanism of the eagre, the information amount is limited. The unmanned aerial vehicle has the advantages of maneuverability, flexibility, wide detection range and the like, and more comprehensive tidal bore flow velocity information can be acquired. According to the tidal line detection method constructed by the invention, the influence of water waves and waves on the river surface is effectively avoided, the tidal line in any form is identified, and accurate point location information is provided. The tidal bore flow velocity measurement method provided by the invention has the advantages of large measurement space scale, accurate tidal head line identification, high non-contact safety and the like, can meet better tidal bore flow velocity measurement requirements, and provides more comprehensive data support for research of tidal bore propagation rules.