The imaging quality of a space-borne camera is key to accurately obtain remote-sensing data. Exposure is an important parameter in the design of a space-borne camera， which affects the image quality of the camera. Auto-exposure obtains information from the target scene in advance and uses it as the basis for determining the exposure， which can avoid the loss of image information by overexposure or underexposure. In order to obtain high-quality image data from the high-resolution camera in Tianwen-1 under the complex illuminance of Mars， an auto-exposure imaging circuit， based on TDI CCD push-broom and CMOS staring imaging， and an FPGA-based auto-exposure algorithm is proposed. The auto-exposure experimental results from the high-resolution camera in Tianwen-1 show that the dynamic transfer function MTF of the image after auto-exposure is increased by 0.013. In an outdoor test， a comparison of the actual scene before and after the auto-exposure shows that the effect of auto-exposure is good， with better scene adaptation. The proposed circuit has the ability to meet the requirements of auto-exposure imaging under the complex illumination of Mars.