In this paper,regions with different implantation areas were prepared on the HgCdTe very long wave 320×256 detector.The diffusion distance and response voltage per unit effective photosensitive area per unit time at different temperatures were obtained by analyzing and comparing the relationship between the signal and the implantation areas of different regions and data fitting,which provides reliable data for the device layout design and performance improvement of the mercury cadmium telluride very long wave detector.