Abstract: Peptides are a kind of very important substance which acts as signals controlling life cycles. Peptides have been well studied in animals, bacteria and fungi as hormones, pheromones and growth factors. An endogenous peptide in a higher plant was first reported as a defense signal named systemin in 1991. Recently, several peptidal plant growth regulating substances were isolated. The discovery, isolation, structure and function of systemin, ENOD40 (early nodulin 40), phytosulfokine and leginsulin are introduced in this paper.