Abstract: As a science, allelopathy is relatively new, even though statements were made about the phenomenon over 2000 years ago. Allelopathy is also a potential research field. Beginning with the concept of allelopathy, this article mainly gives a review of allelopathic research in the recent 20 years. It includes matters, action mechanism, germplasm resource, method of bioassay, hereditary charater of allelopathy. Once more, the importance of allelopathy, the ways to apply the research results in agricultural practice, the challenges for allelopathic research and the directions of future work in this field are also discussed in the paper.