Quantum secure direct communication(QSDC)is a new type quantum communication scheme based on quantum mechanics,which can transmit deterministic information and is more close to classical communication compared with earlier quantum key distribution(QKD)schemes which require auxiliary pre-distribution of secret key,and has become an important branch of quantum communication in recent years. A comprehensive review is presented about the present development of QSDC,with typical QSDC schemes based on various quantum principles as well as the comparisons between them. Then the experimental research on QSDC is reviewed briefly and the future direction is prospected in the end.