Abstract: In order to simulate the flood propagation and inundation, a numerical model was established adapting the finite volume method scheme based on adaptive grid. The model takes the 2D shallow water equation as the governing equation, uses HLL scheme to approximately solve the Riemann solution to obtain the interface flux, and uses the WAF scheme to make weighted corrections to the calculated flux, so as to ensure the second order accuracy in time and space, satisfy the TVD condition, and reduce the numerical oscillation. The bottom slope source term is reconstructed by water depth difference, and the friction source term is semi-implicit solved, which ensures the harmony and stability of numerical calculation. The adaptive grid is quadtree grid, and the mesh refinement is carried out in the region with rapid water level gradient. The numerical example shows that the adaptive grid technology can automatically identify the region with large parameter gradient and the boundary between dry and wet, adjust the grid size, accurately simulate the dynamic change of water flow propagation, and can be applied to the actual flood simulation.