AbstractAllelopathy is a phenomenon of direct or indirect, beneficial or adverse effects of a plant on its own or another plant through the release of chemicals into the environment. It affects plant distribution, community formation, and intercrop evolution. It has a consanguineous relationship with biodiversity conservation, agriculture, forestry, and horticulture and is now arousing further international interest. In China, research on plant allelopathy began relatively late and thus has been limited, particularly studies of fern allelopathy. We introduce recent advances in fern allelopathy, including studies of autotoxicity of ferns, and of allelopathic interactions occuring in two ways: (1) sporophytes acting on gametophytes and (2) gametophytes acting on gametophytes. Fern autotoxicity is a type of intraspecific allelopathy, whereby a fern species inhibits the growth of its own kind through the release of toxic chemicals into the environment. Sporophytes acting on gametophytes and gametophytes acting on gametophytes are common phenomena of interspecific fern allelopathy. In addition, allelopathic effects between ferns and seed plants are discussed. Some ferns can compete with seed plants by fern allelopathy to obtain more resources and space, while some seed plants can inhibit the growth of ferns by allelopathy. Fern allelopathy also has relationships with consumption by animals and microbial infection. Insect herbivory can amplify or dampen the effects of fern allelopathy. Activity of microbes may amplify the allelopathic effects of some ferns. Impacts of fern allelopathy on biodiversity are discussed from the different perspectives described above.