This study constructed a moderated mediation model to explore the impact of parent-child communication on English academic engagement. We conducted a questionnaire survey among 21,270 middle school students using various measurements: English Academic Engagement Scale, Adolescent Parent-Child Communication Scale, learning adaptability questionnaire, and English Learning Self-Efficacy Scale. The results showed that learning adaptability played a mediating role between parent-child communication and English academic engagement. Moreover, the relationships between parent-child communication and English academic engagement as well as between parent-child communication and learning adaptability were all moderated by English learning self-efficacy. These findings revealed the importance of parent-child communication in middle school students' foreign language learning and suggested that more attention should be paid to improving middle school students' English learning self-efficacy and learning adaptability and, therefore, English academic engagement.