In this paper, the differences in installed performance between early domestic medium-wave 320 × 256 infrared focal plane detector components and their foreign counterparts are analyzed. Three experimental methods are employed to test the photoelectric performance of detector components at home and abroad. By analyzing the photoelectric conversion and structure of the detector components, it is determined that the reflection of stray light inside the cold screen is the reason for the difference in the test results, and the blackened layer on the inner surface of the cold screen and the form of its structure are key to the practical application of the component. The improved structure of the cold screen effectively improves the practical application performance of domestic detector modules.