Abstract: To study the insect-resistant mechanism of transgenic ChIFN-γ tobacco,the protease activity of tobacco budworm after feeding on fresh tobacco leaves,tobacco volatile components,and the epidermal trichome density were investigated in the current case.The results showed that insects had a smaller quantity of transgenic tobacco leaves,which may result in less body endocrine protease and lower activity.Compared with the wild type (WT,control),the T0 and T1 generation of transgenic tobacco demonstrated an obviously higher contents of Duvatriendiol and 4,8,13-Duvatriene-1,3-diol.The density of trichome in transgenic tobacco leaves was 49.2% higher than WT.It possibly happened when some transcription factors were activated by ChIFN-γ and bind the cis-regulatory elements of trichome development-related genes,increased the expression of the trichome-related genes,consequently led to the secretion of terpenoid,which may be ascribed to the main mechanisms of the transgenic ChIFN-γ gene tobaccos.