For the high-cost and destructive sample test of a proportion, such as the acceptance test of missiles hit ratio, the fuze reliability and so on, how to reduce the cost is the focus of management and researching. In this paper, based on the Bayesian analysis for qualification test, a truncated sequential assurance test TA for the success/failure success rate P$ was studied,and the design steps of the assurance test TA was also presented.Through the study on the operation characteristic curve (OC) and the average sample number (ASN) curve of the assurance test T A, it shows that when the product quality is on a high level, assurance test TA has an almost equal probability level to pass the acceptance test with the original test T OA; at the same time,it has a remarkable reduction on the average sample number, thus it can greatly reduce product sample test cost. In the end, real example was presented to verify the excellent characteristics of the sequential truncated assurance test TA proposed here