By means of the historical landslide hazards data and the corresponding hourly precipitation, taking Huaping Station of Yunnan Province as an example, the effective rainfall days and the corresponding antecedent precipitation are calculated. The method of principal components analysis is applied to study the impact of the rainfall factors on the occurrence of landslides in order to understand the contribution of antecedent precipitation. The results show that the antecedent precipitation, occurrence precipitation, and excitation precipitation are important for the occurrence of landslides. The weighted relation between antecedent precipitation and occurrence precipitation is discussed. The landslideinduced rainfall includes shortterm heavy rainfall and prolonged lowintensity rainfall. The relation of rainfall intensity to duration thresholds, which contains two types of rainfall characteristics, is obtained for the initiation of landslides at Huaping. A method for defining the end point of rainfall duration and issues needing further study are discussed. The findings about warning rainfall thresholds for Huaping Station can be used as a reference for determining warning rainfall thresholds for landslide disasters.