The objectives of this research are to identify the stage level of English vocabulary mastery of children aged 5-6 and to explore the strategies employed in mastering English vocabulary at the Chinese Champion Tutoring Center. The Tabor and Snow theory is applied to the four stages of English vocabulary mastery, alongside Oxford’s language learning strategies, to determine the methods employed for children aged 5-6 in mastering English vocabulary. Following observations of the children and interviews with their tutors, the researcher discovered that three of the children had progressed to the telegraphic speech stage, while one child had advanced to the productive language stage. Additionally, the researcher identified four learning strategies utilized in the English vocabulary mastery process for children aged 5-6 at the Chinese Champion Tutoring Center: memory strategy, cognitive strategy, metacognitive strategy, and compensation strategy. The cognitive and memory strategy found to be the most used strategy during the process. Lastly, the benefit of this research is to provide valuable insights into how children particularly aged 5-6 mastering English vocabulary, while also highlighting the different factors that influence their development and the stages they achieve.