In this paper, 20 cases of the prefrontal torrential rain in Guangdong Province from April to June of 2015-2017 were selected, and the distribution characteristics of ensemble dynamic factors of the warm-sector torrential rain were analyzed by using the GFS 0.5°×0.5° data. The results are as follows. (1) Among the four types of warm-sector torrential rain in Guangdong Province, the correlation between the ensemble dynamic factors and the accumulated precipitation is the highest in the prefrontal trough torrential rain, followed by the southwest jet torrential rain and the lowest correlation is with the backflow torrential rain. There are common ensemble dynamic factors between the prefrontal trough and the backflow torrential rain, and also between the high-level trough and subtropical jet torrential rain and southwest jet stream torrential rain. (2) Three orders of magnitude weighting index are constructed by different ensemble dynamic factors which are the best representation of precipitation in various warm-sector torrential rains. The index (magnitude is 10-3, 10-1 and 102 respectively) is found to be increasing with the increase of precipitation level, which indicates that the index has a good indication for judging the precipitation intensity. (3) The median of each magnitude index is used as the threshold to judge the precipitation intensity, providing an objective norm for the quantity forecast of precipitation. These results further promote the practical application of ensemble dynamic factors in the prediction of warm-sector torrential rain in South China.