The purpose of this study was to examine the relationships of children’s social behaviors and their age, family factors and extra-curricular activities. The study recruited 193(K1 to K3) children from kindergartens in Macau. The ‘Questionnaire of Family status, Parenting Style and Extra-curricular Activities of children’ and ‘children’s social behavior scale’ were used for measuring such relationships, if any. Data were analyzed through statistics, Pearson Product-moment Correlation. Questionnaires were used in this research, the major findings were as follows: Firstly, 3-6 years old children whose social behaviors in general showed partial positive results. Moreover, the older the children, the more they performed positive social behaviors. Secondly, the family factors were studied children of higher socio-economic status, showed less withdrawal behaviors. Moreover, the higher the level of a father’s occupational ranking, the friendlier the children’s behavior and the more independent the children’s behavior. However, the realationship between parenting style and children’s social behavior was not significantly correlated. Thirdly, Children participate in more sports extra-curricular activities, the less aggressive the children’s behavior and the less distracted the children’s behavior, and the more positive social behaviors; children participate in more language classes extra-curricular activities, the less the withdrawal the children’s behavior, the more independent the children’s behavior; children participate in more art extra-curricular activities, the less aggressive the children’s behavior; children participate in more home economics class extra-curricular activities, the less withdrawn the children’s behavior, the friendlier the children’s behavior and the more prosocial the children’s behavior. Based on findings above, some suggestions were made for parents, kindergarten teachers, governmental organizations and further research. Key word: children’s social behavior, parenting style, extra-curricular activities