Trichomes are derived from the extension of plant epidermal cells and are a unique structure. trichomes can be divided into glandular and nonglandular trichomes. Glandular trichomes are secretory trichomes where a large number of secondary metabolites are synthesized, stored and released. Glandular trichomes often secrete different types of defensive substances such as terpenes, amino acids and phenylpropanes, acylsugars, fatty derivatives, etc. These secondary metabolites can protect plants from biotic and abiotic stresses and have important defensive effects. Therefore, this article summarizes the types of glandular trichomes, the synthesis and regulation of defense substances, and focuses on the study of its synthesis pathways, regulation mechanisms and transport mechanisms to provide references for the research on the biosynthesis and genetic improvement of defense substances.