The invention discloses a runoff calculation method considering maximum depression reservoir depth probability distribution, and relates to the field of hydrological model parameter setting. Accordingto the method, the uncertainty of the parameter of the maximum depression reservoir depth is considered; by supposing that the reservoir depth of the same underlying surface depression is in certainprobability distribution within a certain range, the improved runoff production model can effectively solve the problem that a calculation unit cannot produce runoff when the depression reservoir capacity of the basin runoff production model is small, the mechanism of the model is closer to the actual runoff production process, and a new thought is provided for mechanism research and parameter setting research of a basin hydrological model.