Abstract: In order to improve the reliability assessment of an explosive initiator with small samples, the up-down test was studied. And a new arithmetic was put forward to transform the binary data into virtual complete samples. The simulation result shows that the estimate of the scale parameter from the virtual samples is better than that from the binary data while the estimates of the location parameters are approximately the same. Then using the estimates, a reliability assessment method for explosive initiator based on fiducial inference was proposed. The method was used for the reliability assessment of one explosive initiator, and was compared with the run-down method.