Allelopathy is an active research area of ecology.There are different opinions on the important problem,such as why the plant produces and releases the allelochemicals,and under which conditions,it does so.Allelopathy and allelochemicals induced mechanism under the environmental stress were reviewed in this paper.It is pointed out that the producing and releasing of allelochemicals are formed by the plant under the selective pressure of environmental stress,and allelopathy is an adaptation mechanism of plan...