A new method,based on test information entropy equivalence,for assessing reliability of initiating devices is presented. The method can be used to solve the problems which exist in GJB376 and GJB377. Less than 300 products are sufficient for estimating reliability of 0.999 by this new method and the result is consistent with that of the large sample assessment method. The verification test shows the method is suitable for reliability assessment of iniating devices.