The invention provides a hydrodynamics flood routing analogy method based on a double-
deck asynchronous iteration strategy. Grid data with the same resolution ratio as a 
digital elevation model are used for representing flood data, and the actual 
water flow process is simulated by adopting a double-
deck asynchronous iterative 
algorithm; a flood routing moment is determined by an outer layer 
iteration process according to the given iterative step length, the magnitude relationship between the time used for flowing from one grid to an adjacent grid and the grid iterative step length is compared by an inner layer 
iteration process to determine the respective inner layer iteration step length of grids, the self-
adaptive selection of iterations is thus realized, the fracture 
surface water yield of each grid is subjected to iterative computations, and a flood routing graph is dynamically drawn by setting a time interval of outputting a flood form. FloodArea 
software, a homogenization iterative 
algorithm and the method provided by the invention are adopted for respectively simulating 
storm flood historical data of Fujian province Wanan 
drainage basin, a result indicates that the simulative result provided by the method is highest in 
goodness of fit with the actual disastrous situation, and the flood routing 
simulation precision is effectively promoted.