In the existing research, scholars have different views on the concept and structure of metacognition. Based on different theories, they produce different training methods of metacognition strategies. However, because the training design and training process in the experiment are too complicated and the time is difficult to control, it remains difficult to effectively extend this kind of training to more educational fields. This paper deeply integrates the optimization theory with the case teaching of college students’ English writing in undergraduate colleges and proposes the optimal design of the case teaching process. The optimal design is mainly carried out according to four processes: English writing education consultation, English writing teaching case compilation, English writing case teaching implementation, and English writing case teaching evaluation. In ordinary English writing, students focus on four aspects: preplanning, selective attention, self-monitoring, self-evaluation, and adjusting, controlling, and managing one's own cognitive activities according to self-monitoring metacognitive strategies, mastering the optimization theory, and adjusting the writing speed are self-adjustment and self-evaluation according to one's own situation. In the selected dimensions of English writing, the mean of the postwriting test was higher than that of the prewriting test. The mean of the “average sentence length” increased from 8.6 to 19.1. Integrating metacognitive strategy training into English writing teaching can improve students’ English writing ability.