Abstract The purpose of this study was to understand the impacts of high-grade homeroom teachers' emotional management, positive discipline and social support on the effectiveness of classroom management in Changhua County elementary schools. We started with a questionnairesurvey, used stratified proportional sampling to extracting 330 samples from ChanghuaCounty elementary school’s high-grade homeroom teachers.The statistics methods included Pearson’s product-moment correlation, hierarchical regression analysis andstructural equation modeling to check each hypothesis. The major findings of this study were as follows: 1. Emotional management has a significant positive effect on positive discipline. 2. In the effect of emotional management to positive discipline, social support does not have a significant moderating effect. 3. Emotional management influence classroom management effectiveness by means of intermediate effect of positive discipline.