The dynamic clamping method of space remote sensing cameras was proposed to solve the above-mentioned problem. The method can realize adequately quantization of scene information by subtracting the value of atmospheric path radiation at the analog front end of camera. Imaging chain model for space remote sensing cameras was established first, and the effect of atmospheric path radiation on the image grey-scale area was analysed. Then, the dynamic clamping camera was developed, therefore the analog signal subtracted from the camera hardware circuit was implemented. Besides, experiments were carried out to test the dynamic clamp camera. And the value of atmospheric path radiation calculated by MODTRAN software was converted to value of camera clamp in experiments. Experiments results showed that, the low end information of camera can be fully used by this method, and the image grey-scale range increases by 62 percent. Thus low end quantitative information can also be adopted by designing dynamic clamping for space remote sensing cameras. Then the information of targets can be represented by more quantization bits, and the radiometric resolution is improved as well as more details information of image are remained.