In this study, the relationship between emotion regulation and emotion understanding skills of preschool children and emotional socialization behaviour of mothers was investigated. This study was designed as a correlation type relational survey model with a total of 180 participants - 90 children between the ages of 3-6 and 90 mothers - who have low, medium, and high socio-economic levels. The data of the study were collected using the Coping with Negative Emotions of Children Scale, Emotion regulation Scale, and Wally Emotion Test. The analysis of data was made with multiple regression analysis. The results of the study showed that emotional socialization behaviour of mothers was a significant predictor of emotion regulation skills of preschool children. Problem based and punitive reactions of mothers that are included in emotional socialization behaviours was identified as significant predictors of emotion regulation skills of children. Accordingly, as problem based, and punitive reactions increased, emotion regulation skills of children also increased. However, the results of the study showed that emotional socialization behaviour of mothers was not a significant predictor of understanding emotional skills of preschool children. Based on the research findings, it is suggested that policy makers, institutions educating teachers or teachers themselves prepare early intervention programs to be implemented in pre-schools to ensure mothers' emotional socialization behaviors recognize the potential effects on their children and to support children's emotional development.