Torpedo working reliability assessment comes up against the condition of lacking sample, because of increasingly long lifetime and restricted reliability test by expenditure. In recent years, technical experts usually mine prior data combined with reliability test data to solve the problem using Bayes method. Considering that the existing prior data acquiring doesn't cover the performance reliability information, the Bootstrap simulation method is used to obtain the performance data as the prior data utilized by Bayes reliability method, which tremendously relieves the influence of lacking prior information on reliability assessment and has practical engineering value.