Plant signal peptides are generally 5—60 amino acids in length, derived mainly from three origins. More and more signal peptides have been identified since the first plant signal peptide, systemin, was reported to be involved in the response of tomato to wounding caused by insect or pathogen attack in 1991. There is increasing evidences showing that plant signal peptides play diverse roles in growth, development and bio-/abiotic stress responses. In this review, we summarized the research progresses in plant signal peptides focusing on the aspects of the origin, identification and regulation, and discussed what remain to be addressed in the future.