Abstract: This paper introduces a theory of cutting-off-tail distribution at two ends on the basis of theoretical distributions, in which the stress is a fuzzy variable and the strength is random one. The new reliability design method, combined with the traditional way, is applied in the design of the anti-explosion robot. The new method eliminates the past traditional way, which simply relies on the experience, developing a short-time and long-interval special robot, and shortening the development cycle.