The invention discloses a silt tidal flat topography evolution method based on an oblique photographing three-dimensional reconstruction technology. The silt tidal flat topography evolution method comprises the following steps: planning an air route of an unmanned aerial vehicle in a target measurement region of a tidal flat and distributing and uniformly driving positioning piles in the region; fixing a flying disc on the piles to be used as a control point; carrying out static data acquisition on the control point by adopting a GPS (Global Positioning System); acquiring aerial photographs ofthe region by utilizing the unmanned aerial vehicle; generating a point cloud and an ortho-image of the region through the photographs photographed by the unmanned aerial vehicle by utilizing three-dimensional modeling software; identifying a water ponding region from the ortho-image and eliminating the water ponding region from point cloud data; coupling acquired static data into the processed point cloud data and establishing a three-dimensional model of the region, so as to obtain tidal flat elevation information of the region; verifying model errors by utilizing a Rod-SET system; carryingout periodic monitoring modeling on the same region, so as to monitor scour and silting evolution of the region. The silt tidal flat topography evolution method disclosed by the invention has the beneficial effect that the elevation precision of topography measurement reaches a centimeter grade.