Abstract: To investigate the pulse excitation ignition mechanism of installed hot bridge wire electro explosive devices (EEDs) and to provide theoretical and data-driven support for their susceptibility equivalence testing under narrow-band HPM irradiation, based on the heat transfer model of hot bridge wire EEDs and the numerical calculation results of critical ignition current, and taking into consideration the physical mechanisms underlying the ignition process of hot bridge wire EEDs, the relationship between pulse excitation parameters and critical ignition current was derived through fitting, and a mathematical model for critical ignition current under pulse train excitation was proposed. Furthermore, based on theoretical and simulation analyses, pulse current injection sensitivity tests were conducted to measure the 50% ignition current of No. 7A, No. 8, and No. 8A hot bridge wire EEDs under pulse excitation with varying parameters. The mathematical expressions linking the 50% ignition current to pulse excitation parameters for these three EED types were subsequently established. Experimental results demonstrate that the proposed mathematical model for critical ignition current under pulse train excitation exhibits an error margin below 10%. Additionally, the thermal time constants of No. 7A, No. 8, and No. 8A EEDs were determined as 3.96, 3.75 and 28.9 ms, respectively.