A new analysis method of reliability tests for explosive initiator was proposed to improve the analysis of reliability tests for explosive initiator with small sample size. The reliability data were collected by Langlie test,and then were processed to be order restricted with the isotonic regression. The new parameters estimates were obtained from the order restricted data. The simulation was used to compare the efficiency of the new estimates with the traditional estimates,and the result shows that the new estimate of location parameter is better. The present method was used to assess the high reliability of one initiating device with small sample size. And the feasibility and applicability are validated, compared with the rundown method.