Numerous lepidopteran adults frequently pick up plant pollen when feeding. Identifying plant species visited by Mamestra brassicae moths could further strengthen our knowledge of their migratory trajectory and the interactions of M. brassicae moths with these plant species. Here, with morphological analysis and DNA metabarcoding of pollen carried by the moths, we determined these plant species visited by M. brassicae during 2015–2018. Pollen grains removed from M. brassicae moths were identified from 25 species (18 were identified to genus), representing at least 19 families, including Pinaceae, Oleaceae, Rosaceae, and Asteraceae, but mainly belonging to Angiospermae, Dicotyledoneae. There were noticeable interannual differences (maximum value: 35.31% in 2018) and seasonal differences (maximum value: 33.28% in April–(including May)–June) in the frequency of M. brassicae moths with adhering pollen, but no noticeable difference based on sex. Meanwhile, we also found pollen from some species such as Citrus sinensis (Rutales: Rutaceae) and Melia azedarach (Rutales: Meliaceae) that grow in southern China, indicating that M. brassicae moths might migrate northward in spring. Our results demonstrate that the M. brassicae moth visits a variety of plant species during migration, and these findings promote our understanding of the interaction between moths and these plant species.