This study surveys the reality of sex education for 5-6-year-old children through learning games in some preschools in Lam Binh district, Tuyen Quang province. Survey results show that children's level of understanding about gender is mainly at medium and weak levels. The main reason is that preschool teachers have not used many methods of organizing learning games to educate this content in children. Moreover, the content of sex education implemented is only at the level of integration and integration into life skills education activities and is implemented mainly on the topic of self. From there, the author proposes some measures of sex education for 5-6 years old children through learning games in the survey area.