Abstract：A multidisciplinary approach based on logistic regression and antecedent effective rainfall was adopted to study the very complex phenomenon of rainfall-triggered debris flows. An integrated method for quantitative analysis of critical rainfall has been promoted. And a test of this approach was applied in Xiuyan，Liaoning Province. Rainfalls are the main inducement factors of debris flows in China. So it is very important to study the relationship between rainfall and debris flows. But many different subjects such as geology，meteorology，hydrology and agrology are mutually acted. So there is not any universal method to calculate the critical rainfall. The rainfall days when debris flows happened or not were collected from rainfall stages. Then point rainfall was converted into surface through isoline method. Thus，the rainfall corresponding to the happening of debris flows was obtained. The rainfall samples of safe days were gained through counting ahead；and the most suitable days for analysis were computed through logistic regression. Then the rainfall and the antecedent effective rainfall of samples were analyzed based on logistic regression. Experiential value(0.84) and actual value(0.61) were respectively adopted as the effective rainfall coefficient. The actual value was computed with precipitation rainfall data and hydrological data of Xiuyan. The good classifying ability of this method was approved，and a quantitative prediction of debris flows was achieved and the effects of using two different coefficients were both satisfying.
