Abstract:Since Comprehensive Test Ban Treaty to ban all nuclear weapons test explosions has been passed, Quantification of Margins and Uncertainties(QMU) for certifying the availability of the Nuclear Stockpile in the USA is a newly presented method. It is able to reveal the failure fact efficiently and give QMU in assessment combining with the information of tests and numerical simulations. Although QMU is still under development, it can provide a reference for the effectiveness evaluation of complex systems. The determination of the critical characteristic parameters is one of the key techniques in QMU. In this paper，a method is presented to quantitatively analyze the relational degree between the requests on critical characteristic parameters and the characteristic parameters，by utilizing the uncoiling matrix of critical characteristic parameters，then the critical characteristic parameters of the product are determined.