The purpose of the study is to use systematic review and meta-analysis to investigate the effects of aggressive reduction programs for early childhood. For a systematic review and meta-analysis, through the KISS, RISS, National Assembly Library and DBpia database with ‘early childhood aggression & program’,‘early childhood aggression & active’,‘early childhood aggression & reduction’as searching key words, 45 studies of aggression reduction program were selected in accordance with the purpose of this study. In this study, 45 studies were included within systematic review from 1997 to 2018. And 44 studies were included in the meta-analysis except 1 study which statistical figures have not been analyzed yet.
The main issues and results of this study were as follows:

1. What is the total effect size of the aggression reduction programs to early childhood’s aggression reduction?
2. How different the effect on each sub-type aggression(substitute aggression, personal aggression, verbal aggression, mixed aggression)of the aggression reduction programs?
3. Is there a difference in the size of the effect on early childhood’s aggression depending on the type of aggression reduction programs(Social relation area, Artistic experience area, Physical exercise and health area)?
4. Are there any difference in the effect size of early childhood’s aggression reduction according to the moderator variables?

First, the data of 44 studies were calculated to figure how the program has effected to the result, and it came with great effect of the aggression reduction program which has resulted ?1.2265 with 95% confidence interval of ?0.9514 to ?1.5016.
Second, the effect size of each sub-factor of the aggression reduction program showed the significantly differences. The effect size of the sub-factors of aggression was substitute aggression(-0.8562), personal aggression(-1.1370), verbal aggression(-.0.9543) and mixed aggression(-1.0239). But there was no statistically significant difference between the groups.
Third, there was a difference in the effect size of effect on the aggression reduction depending on type of aggression reduction program. By ordering the greatest effect of aggression reduction program type was social relation (-1.8377), art experience(-1.0094), physical exercise and health(-0.9147). Social relation showed the greatest effect size on reducing aggression.
Fourth, the moderator variables affecting the mean effect size for the aggression reduction were not statistically significant. In other words, this study has not revealed the cause of heterogeneity.
The results of this study by using systematic review and meta-analysis will be the great evidence-based data on the data for further studies of aggression reduction prevention and aggression reduction programs in early childhood.