Aiming at the problem that the brightness gains of super Gen. Ⅱ image intensifiers, equipped with high-voltage DC power supplies, substantially decrease at high temperatures, according to the theoretical analysis, this study developed high and low temperature test platforms to study the temperature characteristics of an image intensifier with a high-voltage DC power supply, an image intensifier tube, and a single high-voltage DC power supply. The experimental results show that the brightness gain of this type of image intensifier at a high temperature (55℃) decreased by approximately 65% than that at a low temperature (-55℃). However, on supplying constant cathode, MCP, and anode voltages to the image intensifier tube, the brightness gain decreased by 20%, which was mainly due to the decrease in the cathode sensitivity and luminous efficiency of the fluorescent screen with the increase in temperature. Compared with low temperature (-55℃), the cathode voltage of the high-voltage DC power supply was reduced by approximately 40 V at high temperature (55℃), whereas the MCP and anode voltages were reduced by approximately 18 and 100 V, respectively. These three factors accelerated the attenuation of the brightness gain of the image intensifier at high temperatures. Therefore, compensating the cathode, MCP, and anode voltages using software and/or hardware to the power supply can be an effective method to improve the brightness gain consistency of super Gen. Ⅱ image intensifiers with a high-voltage DC power supply at various temperatures.