The purpose of this research was to determine the relationship between preschool children's aggression and family structure with the mediation of parents' socio-economic factors.

This research was a descriptive-causal-comparative type. The statistical population of the was made up of all preschool children in Tehran, and 100 of them were selected as a sample based on Cohen's formula and by multi-stage cluster random sampling. To collect data, socio-economic status questionnaire (2013), marital satisfaction questionnaire of Enrich (1998) and aggression questionnaire of preschool children by Vahedi et al. (2017) were used. The data were analyzed using the SPSS23 method, central and dispersion indices such as the mean and standard deviation were used to summarize and describe the information, and the hypotheses were examined using the method of examining the homogeneity of the covariance matrix of the dependent variable and the skewness and kurtosis of the distribution of the variables, and the answer to the hypothesis.

The regression results showed that the higher the level of parental marital satisfaction, the lower the level of children's aggression. It was also found that socio-economic factors do not have a significant mediating role between marital satisfaction and aggression and the role of these factors is only a moderator.

According to the findings, it seems that the socio-economic status variable moderates the relationship between marital satisfaction and aggression between parents. Paying attention to improving the economic and social status of couples can play an important role in reducing children's aggression and behavioral problems.