This study considers the design of life test sampling inspection plans by attributes for failure rate level qualification at selected confidence level. The lifetime distribution of products is assumed to be exponential. MIL-STD-690C and KS C 6032 standards provide this procedures. But these procedures have some questions to apply in the field. The cost of test and confidence level(1-β risk) are the problem between supplier and user. So, we suggest that the optimal life test sampling inspection plans using expected cost model considering product cost, capability, environmental test cost, etc.