For high reliability and long-life equipments, regular test on their performance is an effective approach to keep a fine status during the whole life. Because the number of failures increases with the duration of service, it is very important to use a rational testing strategy with unequal testing period instead of equal testing period. If testing period is not suitable, failure cannot be timely found and repaired, early failure or accident may occur. Reliability detection strategy of exponential distribution products is studied. And for every testing period, on the basis of the assumption that products should be tested when the rate of reliability deterioration reaches a certain value, an equal reliability degradation model on testing period is discussed. Furthermore, according to the idea that environment and personnel factors can lead to characteristic deterioration of products, a mathematical model of testing period incorporating reliability, failure rate, cost and testing efficiency is proposed. As the objective function of minimum cost and constraint functions of reliability and testing interval, an optimization model of unequal testing period is put forward. The optimization model is much better than traditional equal testing interval model in maintenance reliability lifetime, for it conforms to the reality that testing period must be shorten when the reliability degrades.