Five new limonoids, named munronoids K-O (1-5), together with three known limonoids were isolated from Munronia unifoliola Oliv. These limonoids were involved in the skeletons of evodulone, gedunin, and peieurianin types of limonoids, and their structures were established on the basis of spectroscopic data. Compound 5 featuring a γ-lactone ring instead of the β-substituted furan ring was found in the peieurianin type for the first time. The antitobacco mosaic virus (anti-TMV) activities of compounds 1-8 were also evaluated with half-leaf, enzyme-linked immunosorbent assay, and Western blot methods, and limonoids 1, 5, and 8 showed stronger anti-TMV treatment activities than the positive control ningnanmycin. Six compounds (1-5 and 8) exhibited infection inhibition activities against TMV.