Chitin biosynthesis and degradation is one of the most important physiological processes in insects. Insect chitin biosynthesis pathway starts from trehalose and ends with chitin, in which 8 enzymes are involved. Trehalases and chitin synthases (CHS) have currently been studied at most. There are two trehalases in insects, soluble and membranebound trehalases, with major roles in chitin synthesis in the cuticle and the midgut, respectively. The class A CHS is involved primarily in chitin synthesis in the cuticle and trachea, while class B CHS is thought to be for synthesis of chitin in the peritrophic matrix. At present, chitin biosynthesis can be regulated in two aspects such as use of RNAi techniques and chitin synthesis inhibitors.