These grid units with the same routing order can be computed in parallel because these grid units do not have upstream and downstream dependencies. The grid units of each routing order are counted to obtain the distribution table of the parallel routing order of the watershed. Table 1 shows the distribution table of the parallel routing order of the Tunxi watershed in Anhui Province. We can find that as the routing order increases, the number of slope grids decreases gradually, and the routing order of the watershed outlet grid is the largest.