Abstract: To find out the role and application of plant allelopathy in agroecosystem, current research achievements in plant allelopathy field, allelopathic plant, allelochemicals and their releasing way were reviewed in this paper. The researches on plant allelopathy in agriculture, forestry and animal husbandry were also concluded. The results showed that plants with potential allelopathy were found in multi-families, such as Leguminosae, Gramineae, Compositae. More than a dozen of allelochemicals were identified such as terpenoids, phenols, alkaloids, and so on. Allelochemicals got into the surrounding environment by natural evaporation, fog leaching, root secretion and residue decomposition, and then the allelopathy occurred in the receptor. Different concentrations of allelochemicals had different promoting or inhibiting effects on seed germination and seedling growth. Allelopathy played an important role in crop rotation and intercropping, species selection in mixed forest, reasonable grazing and herbicide. Finally, based on current progress of allelopathy, we pointed out and analyzed the key problems of allelopathy in agroecosystem.