Considering the low efficiency of large-scale channel terrain rendering，this paper constructs the triangular terrain grid through discrete water depth data of channels and uses the idea of LOD to control and display the density of grids. Specifically，the method based on the Delaunay triangulation is used to construct the channel terrain，and the alpha-shapes boundary extraction method is employed to optimize the Delaunay triangulation. A grid division method is proposed to control the density of grids. Moreover，a suitable variation model is selected through the comparison of the fitting effects by the Kriging interpolation model to solve the problems of insufficient sampling of water depth points and low efficiency of scene rendering. The application results indicate that the method can be used for real-time rendering of large-scale channel terrain.