As for the failure probabilities pi（i=1

…

m） falling in(0

ti] in zero-failure data analysis

the paper presents a new method of amending the prior distribution of pi by using the hybrid distribution of m-1 approximate distributions of pi.One kind of monolayer Bayes iterative estimators and hierarchical Bayes iterative estimators for failure probabilities are given.The two iterative methods are applied to hydraulic pump data analysis.According to the maximum likelihood principle

the choice of λm values is discussed.By comparing the two iterative methods

the conclusion is obtained that the hierarchical Bayes iterative method is superior to the monolayer Bayes iterative method in terms of the robustness in the choices of λm value

but the hierarchical Bayes iterative method requires more calculations.