Two-dimensional magnetic materials are the focus of condensed matter physics. Recent experiments have found that bulk CrI3 shows an interlayer ferromagnetic order, whereas its bilayer possesses interlayer antiferromagnetism, which shows the quantum confinement effect and potential device applications, and has attracted widespread attention. Many studies have shown that interlayer magnetism is closely related to stacking order, but it is still controversial. This paper reviews the main research on the interlayer magnetism of bilayer transition metal trihalides and its application. Firstly, we introduced the relationship between the interlayer magnetism and stacking order, and then pointed out the density functional theory’s challenges in describing the interlayer magnetic mechanism. Finally, we expounded on the interlayer magnetism-related device applications and proposed the future research direction.