Abstract: The active Yellow River mouth is an emerging landform formed after the artificial diversion of the river channel to the Qing 8 in 1996. The tidal flat there is silty and difficult to reach. As the results, tidal flat elevation data is lacking. This study used a method that may construct tidal flat elevation with the Delft3D hydrodynamic model and waterlines. The waterlines from August to the end of November of 2014 were extracted using the SVM supervised classification and Sobel edge detection from the domestic GF-1/WFV satellite images, and the corresponding tidal levels were simulated with the Delft3D hydrodynamic model. Elevations were assigned to the waterlines, thus the simulated digital elevation model was obtained. Compared with the measured data, it is observed that the errors between the simulated DEM and the measured DEM fall in a limited range of -38 to 38 cm, with a mean less than 10 cm. This method may provide effective data support to the study of tidal flat morphological evolution in the areas lacking of measured data.