This study aims at investigating the effects of mothers’ coaching ability on their children’s happiness and the moderating effects of young children’s autonomy. This study collected data from 290 children who were 5 years old and attended in kindergarten in Daegu city and 290 mothers of theirs. Data analysis conducted Pearson’s correlation and multiple regression analyses using SPSS 21.0. For exploring effects of mothers’ coaching capability on their children’s happiness and the modulating effects of young children’s autonomy, multiple regression analysis was conducted. The findings were as follows: 1) the variables of mothers’ educational backgrounds, parental training experiences, and their incomes were positively and significantly related with their coaching capabilities. 2) Mothers’ coaching capabilities had significant effects on their children’s happiness. Among the subcategories execution capability had the highest effect and then, relation and consciousness capabilities follows in order. 3) Children’s spontaneity, pursuit, and superiority among the six subcategories of children’s autonomy had significant moderating effects on children’s happiness. This study provides useful data for developing parental training programs that can facilitate and improve parents’ coaching capability for improving their children’s happiness.