This study surveys the actual situation of vocabulary development for 5–6-year-olds children in some preschools in Ho Chi Minh city. The results revealed main issues such as: Preschool teachers' awareness of the importance of using games for vocabulary development; Methods for teachers to design and organize vocabulary development games and evaluate their effectiveness; Difficulties in creating engaging games for this age group. Additionally, the study explores teachers' perspectives on game design and assesses children's vocabulary development levels. This study provides valuable practical insights to assist preschool teachers in designing vocabulary development games for 5-6-year-olds, thereby promoting overall language development.