Abstract: The sensitive frequency of electro-explosive devices in EMI is analyzed based on field coupling to line theory. Firstly, the transmission line model of electro-explosive device is built up. Then, the formula of absorption power and incident frequency is given. The influence factors of sensitive frequency are drawn by means of numerical simulation. The simulation results showed that the sensitive frequency of electro-explosive device is decided by the length of its pin. Whether electro-explosive device with the same pin length is open or short, the sensitive frequency remained the same. These results are useful for RF hazard analysis of electro-explosive devices.