Shadow education, also widely known as private tutoring or supplementary education, has attracted increasing research attention in the past two decades. The global expansion of shadow education, as well as its penetration to different educational stages and social classes, are believed to have far-reaching implications for the overall educational landscape. However, despite a steadily growing body of literature, no study to date has systematically reviewed the influences of shadow education from an ecological perspective. Therefore, borrowing Bronfenbrenner's ecological systems theory, this paper aims to provide a comprehensive overview of how shadow education influences different levels of educational ecosystems (i.e. individuals, micro-, meso-, exo-, and macro-system). Based on 74 empirical studies published between 2000 and 2020, the review reveals complex influences exerted by shadow education on multiple systems (e.g., students, mainstream schooling, families, and larger socioeconomic structures), contributing to a more sophisticated understanding of this phenomenon. The paper then discusses how the rise of shadow education creates significant changes to the ecology of education in which it operates, and concludes with implications for future practice and research.

影子教育，也被广泛称为私人补习或补习，在过去的二十年里越来越受到研究的关注。影子教育在全球的扩张，以及对不同教育阶段和社会阶层的渗透，被认为对整个教育格局产生了深远的影响。然而，尽管文献数量稳步增长，但迄今为止还没有研究从生态学的角度系统地回顾影子教育的影响。因此，借用布朗芬布伦纳的生态系统理论，本文旨在全面概述影子教育如何影响不同层次的教育生态系统（即个体、微观、中观、外部和宏观系统）。根据 2000 年至 2020 年间发表的 74 项实证研究，审查揭示了影子教育对多个系统（例如，学生、主流学校教育、家庭和更大的社会经济结构）施加的复杂影响，有助于更深入地理解这一现象。然后，本文讨论了影子教育的兴起如何对其运作的教育生态产生重大变化，并总结对未来实践和研究的影响。