The factors which dominates the occurrence of debris flow are different. What we pay attention to in researching and predicting the occurrence of debris flow should not be the same. On the basis of these dominating factors and according to the characteristic in Southwest China, we can divide these areas into four parts, namely precipitation dominating area, earth source dominating area, temperature dominating area and compound factor dominating area. (1) In the precipitation dominating area, the soure of soil is abundant and the function of rainstorm should be mainly considered to predict the debris flow. (2) In the earth source dominating area, precipitation is affluent and the function of accumulated earth amount should be mainly considered to predict the debris flow. (3) In temperature dominating area, glacier debris flows are widely distributed, which are affected by the fluctuating temperature. (4) In the compound factors dominating area, water source and soil source rarely satisfy the debris flow outbreak and the frequency appear low.