Objective: The purpose of this study is to comprehensively analyze the meta-analysis effect size about variable relationship of parental marital conflict affects to aggression. of child and youth and to derive policy implications for reducing this aggression. Methods: For these work, we selected 23 published papers in Korea ( k = 189 ) and conducted meta-analysis in R. The results of the study are as follows. Results: First, the overall effect size of the variable relationship between marital conflict and aggression showed meaningful effect size to both educational and therapeutic. Second, the effect size of the Conflict Properties showed the highest value among the variable group of marital conflict, followed by threats, self-criticism, and triangular relationships. Third, if you check the sub-factors of marital conflict, conflict variables showed high effectiveness in conflict frequency, threat variables in conflict coping efficiency, and self-criticism variables in conflict content. Finally, subjects, variables in marital conflict, variables in aggression, and tools for measuring marital conflict and aggression in the control variable analysis showed meaningful value on the group difference of the lower factor. Conclusions: In order to reduce aggression of children and youth result from marital conflict, various research and policy support should be provided in a step-by-step and systematic way to resolve family relationships, especially for ways to solve marital conflict.