Abstract: This article investigates the problem of reliability assessment for pyrotechnic devices with redundancy design. For the redundancy programs that are commonly used in the design of pyrotechnic devices, the corresponding hardened test programs are formulated, and the reliability of pyrotechnic device under hardened conditions is estimated according to the trial results. Then, combining with the mechanical characters of the products, the reliability under normal conditions can be calculated by a series of formulas. It indicates that using this method, with the confidence level of 0.95, only less than 10 times of successful trials are needed to evaluate the reliability of 0.99990～0.99999. It also shows its high trial efficiency for pyrotechnic devices with redundancy design, and can meet the engineering needs of reliability assessment for the aerospace products.