Abstract: FMECA is the basis of reliability analysis, maintainability analysis and so on. In the criticality matrix, the horizontal axis is severity level, the vertical axis is criticality value of the failure mode or product. However, the failure modes can not be accurately identified while they have the same severity level. And then, that will lead to criticality with deviation and non-optimal improvement decisions. In addition, the efficiency of graphic method is low. A new calculation method of quantitative analysis method of criticality matrix based on the current method is described in this paper, which can be used for improving the precision and efficiency of FMECA. A sample is demonstrated that quantitative value of failure mode or product criticality can be obtained easily, which is the basis for supporting improvement decisions.