In the early stages of weapon system development, it was necessary for testability requirements to have a failure test design alternative, and for the test design solution to be optimized. In light of these aims, current failure mode, effects and criticality analysis (FMECA) shortages were analyzed, and its improving approach was given. Modeling was used to find characteristic indicators of failure tests, as well as their effect levels and effect values. On this basis, a comprehensive evaluation modeling on failure test characteristics was completed, and an optimization algorithm for test design was proposed. A typical demonstration was proven using example data, and the algorithm of this model was then explored. The results and applications showed that the optimization method can markedly improve current test design and afford a theoretical foundation to optimize test design during the early stages of weapon system development.