Abstract: To decrease testing samples and avoid the risk caused by estimated error of scale factor , a new statistical method was introduced in the tests on reliability assessment of explosive initiator. The concept of entropy was presented and the equation of testing entropy equivalence was given. This testing entropy equivalence method for assessing reliability of explosive initiator was put forward according to the distribution function of sensitivity and application of go/no-go and sequential methods together. The feasibility and correctness were validated in the control tests of detonator reliability assessment with large samples compared with small samples. Results show that reliability of explosive initiator with high index can be assessed in small samples.