Microplastics (MPs) are widely distributed in the environment. MP pollution has been found in the environment globally, which directly threatens human health. It is of great importance to study the influencing factors and mechanism of MP migration in the vadose zone to evaluate its distribution and environmental risk accurately. Through a literature review, the source, migration, and transformation of MPs in the vadose zone were summarized, and the influencing factors of MP migration in the vadose zone were systematically expounded. The mechanism of MP migration was analyzed, and future research was suggested. The factors affecting the migration of MPs can be divided into chemical, physical, and biological categories. At present, research on the migration of MPs in the vadose zone is in its infancy. In a further study, the migration of MPs at the field scale, the synergistic migration and transformation of MPs with other pollutants and the mutual feedback mechanism, and the use of the properties and biological functions of the vadose zone to study the role and mechanism of MPs in global carbon neutralization are worthy of attention.