The2-dimentions flow mathematical model is widely used now,but few people has studied the problem of runoff yield and flow concentration in the model region.Based on the simulative calculation of the2-dimentions flow,which occurred in the random flow area on left bank of the collecting channel of the Median-Line South-to-North Water Transfer Project,the problem of runoff yield and flow concentration in both water area and land area of the model region.On the basis of the2-dimentions hyd rodynamic mathematical model,the hydrologic mathematical model and the hydrodynamic mathematical model in the random flow area have been built,a series effective methods dealing with the problem of runoff yield and flow concentration were put forward.