Nonlinear regression model is widely used in rainfall-runoff modeling.However,estimating the model accuracy,partition data for calibration and validation,and feature selection are three main handicaps when constructing the model.Gamma test is a model-independent data analysis method.It can be used to help constructing model and solve over-fitting problem during model training period.This paper firstly introduced the Gamma Test,and gave the general formula of rain-runoff regression model.Then a case study wa...