The invention discloses a layered runoff calculating method for soil in a wet region. The invention provides a runoff yielding sub water source calculating method, wherein water tanks are connected inparallel in the vertical direction and water tanks are connected in series in the transverse direction. The method can reflect the actual layered runoff process of soil in a drainage basin, solves the problem that sub water source calculation in a runoff yielding model in the wet region is short of clear physical meaning, and is of relatively high engineering meaning.