By considering the main elements of runoff yield in a basin based on the relationship betweenthe infiltration capacity distribution curves and the runoff yield process.the author of this paper has taken the rea-sonable structures in the Stanford Watershed Model IV. combined with the traditional antecedent precipitation in-dex(Pa)and established the Runoff Yield Event Modd(RYEM The RYEM has been used for flood forecastingin two watersheds of Danjiang and Xunhe, the tributaries of Hanjiang RiVer The tests show that the qualified ra-tios of runoff yield all exceed 80%,It is believed that the RYEM is both simple and convenient.