Abstract: Plant allelopathy, as a natural ecological phenomenon, is common in nature.Current research mainly focuses on separation, identification, releasing mode, operational principle of plant allelopathy, and allelopathy application potential on sustainable development of grassland agroecosystem including agriculture, forestry, and animal husbandry.However, the specific roles and application of allelopathy in grassland agroecosystem are still lack of deep and systematic analysis.In order to understand the roles of allelopathy in grassland agroecosystem, we firstly summarized the allelopathy mechanism in intraspecific, inter-species, plant and insect, plant and microorganism starting from the material basis of plant allelopathy; then reviewed the latest research achievements of allelopathy in grassland agroecosystem including agriculture, sand xerophytic and grassland; finally pointed out the application value of plant allelopathy in grassland agroecosystem as well as its existing problems.