In this study, we proposed a method to optimize the environmental stress-screening profile of a K-series main battle tank based on a record of environmental stress-screening defects during the mass production of electro-optical systems. The screening strength of the existing ESS profile was analyzed and the ESS profile was optimized by adjusting the operation cycle and temperature change rate to maintain the screening strength of the existing ESS profile. However, it is difficult to apply this optimization method in the early mass-production stage. However, the ESS profile can be adjusted when the quality of a mass-produced electro-optical system is stable. By adjusting the profile, it is expected that the operating time and cost of the test facility can be reduced by optimizing the ESS profile through a quantitative analysis of defects. This optimization method can be applied to similar electro-optical systems and other military electronic products.