With the continuous reform and development of China's education system, the position of metacognition in language learning has gradually been emphasized. The New College Entrance Examination in Jiangsu Province, which is part of China's secondary education curriculum reform, imposes stricter and broader requirements on students' English proficiency. Under this new situation, it is particularly important to study in detail the use of metacognition in the English subject and to analyze the effect of metacognition on students' performance in the English Completed Gaps section of the New College Entrance Examination. In order to better understand how metacognition can help students improve their performance in the English Cloze Exam, this study will take a process in "Flow classroom" of Nanjing No.5 Middle School as a case study. The English curriculum and teaching methods of the "class" in Nanjing No. 5 Middle School are characterized by the school's high-quality teaching resources. The study also emphasizes practice and innovation to develop students' metacognitive skills. Therefore, through empirical cases, it can be better understood the role of metacognition in actual classroom teaching and practical tips to help students achieve better grades in the College Entrance Examination.