A firing reliability design method for hot bridgewire electroexplosive device was put forward. Firstly,the temperature rising model of bridgewire and temperature distribution model of explosive were constructed; secondly,the critical firing energy of explosive was calculated based on energybalance equation and selected parameters; finally,margin of firing reliability of initiator was calculated. If the margin can not meet the reliability requirement of product,parameters would be adjusted and margin of firing reliability would be calculated again. By using the method above and adjusting the design parameters,the critical firing voltage of an electroexplosive actuated device is 4.75 V and its margin is 1.2. The calculation result shows that the product can meet the reliability requirements.