Azadirachin has effects of antifeeding,stomach poison,contact poison,and growthinhibition on many insects. The main mode is disrption of endocrinic activities ininsect.Azadirachtin attacks neurosecretory cells,corpus cardicum prothoracic glands,etc.,causing interruption of synthsis and release of prothoracicotropic hormone(PTTH)in brain,and reduction of receptivity of prothoracic glands to PTTH which acco untsfor the shortage of 20-hydroxyecdysone in synthesis and release. For these reasons,gro wth and metamorphosis of insects were disturbed.The effects of azadirachtin onother tissues relative to synthesis and release of hormones for metamorphosis werealso discussed in this paper.