Launch the emergency response level effectively is a prerequisite for implementing emergency rescue scientifically and reasonablely when natural disasters occur. At present, emergency response grading standard is based on three emergency response indicators, which launches by Ministry of Civil Affairs. It provides the range of each response level’s indicators, however, this scheme lacks quantization scale for elastic adjustment, according to specific disaster. For the above problem, emergency response level classifier was trained in this paper base on C4.5 algorithm and historical cases. It also obtain a reasonable reduction ratio for the traditional emergency response level. Through experimental results of flood disaster show that this method provides valuable reference to reduction ratio.