Abstract: In order to save the test cost for products with high-reliability and long-life testing characteristics, the optimal truncated sequential tests of exponential distribution without substitution is studied in this paper. The theory of truncated sequential optimal test without substitution test is established. The calculation expressions of key statistical feature indexes such as the operating characteristic curve and expected natural calendar test time of the test plans are derived. Sample space sorting method has also been established to solve the optimal truncated sequence test. Through comparison with the test plans provided by the international standard IEC61124, the results show that, as the type I and type II errors probabilities have been strictly controlled, the new test plan proposed here can save nearly 80% of synthesis expected natural calendar test time simultaneously. Moreover, through comparison with the optimal truncated sequential test with substitution, the results show that, the new test plans can reduce nearly 70% of the synthesis expected natural calendar test time. The plans established in this paper significantly reduces the synthesis expected natural calendar test time of the test, thus significantly saving the test cost for products with high-reliability and long-life testing characteristics.