Human milk oligosaccharides (HMOs)， among which lacto-N-neotetraose (LNnT) has been widely used as a nutritional fortifier in infant formula， are attractive in recent years because of their prebiotic function， immune modulators， antiadhesive antimicrobials， as well as modulators of intestinal cell responses. HMOs are divided into non-fucosylated neutral， fucosylated， and sialylated oligosaccharides. As one of the most important core structures of HMOs， LNnT can be modified with fucose residue or sialic acid residue to obtain a variety of derivatives. On account of the widely confirmation of their promising physiological effects， they are credited with significant commercial value and potential in the food and pharmaceutical industry. Therefore， it is nothing strange that the exploration of its synthetic method has become a hotspot of research. Among them， the research process of conventional chemical approaches encounters bottlenecks due to a variety of side reaction problems， while biosynthesis takes advantages of the specificity of enzyme reactions and is developing rapidly. In this paper， the physiological functions and biosynthesis process of LNnT and its derivatives were briefly reviewed， and the advantages and disadvantages of biosynthesis methods were pointed out， then the development of LNnT and its derivatives was prospected.