Abstract: Studies on plantendophyte interactions at home and abroad over the last twenty years are reviewed, beginning with the basic biologic al aspects of the endophytes, and including the detection, identification and artificial infection of the endophytes, effects of their infection on plant growth, development and stress resistance, and future applications of endophytes in agriculture and related industries. A research project of the authors on the effect of endophyte infection on drought resistance of perennial ryegrass is briefly introduced.