Taking the complementary metal oxide semiconductor (CMOS) sensor CIS2521F of Fairchild Company as an example, the optimal integration time in the latest high dynamic range (HDR) technology of dual-channel and dual-gain hardware is analyzed. By analyzing the relationship between the scene irradiance and the gray value of the dual-channel and dual-gain scene and the noise gray value respectively in different integration time in the space environment with noise, 1 ms is selected as the integration time of high and low gain. So the image will not be over exposed under high irradiance, and will not lose details due to noise under low irradiance. And the imaging dynamic range is up to 84.8 dB after the dual channel results fusion.