The purpose of this study is to explore young children’s metacognition expressed during coding play. The children participating in this study consisted of 13 five-year children(6 males and 7 females) at H Kindergarten in S City. Various data, such as observation records, researcher’s own journals, and informal consultation meeting records were collected and analyzed. The results of this study are as follows: First, metacognitive planning can be further activated in coding play while children create their own meaning through judgment and selection. Second, children are engaged in monitoring the degree to which performance is progressing towards a desired goal. Third, metacognitive control actively appeared in coding play while children changed ways of conducting tasks. Fourth, children review task performance and evaluate the quality of performance in coding play. The results of this study are expected to help understand how young children’s metacognition appears in coding play, and further reveal the educational value of coding play that helps young children activate their metacognition.