The research on the interference effect of laser on infrared imaging system is a hot topic recently. At present, there are few researches on the interference of mercury cadmium telluride (be short for HgCdTe) refrigeration gaze thermal imager in medium wave by pulse laser. In this paper, a 3 kHz pulsed laser was used to irradiate the thermal imager. The interference threshold was obtained and the mathematical relationship between the number of saturated pixels and the interference laser power density was obtained by fitting.