Abstract: In the long time astronomical opto-electronic observation system, the mechanical shutter will often be removed to decrease the operating cost But under this circumstance the influence of smear noise on target detection is much serious in fullframe CCD. Based on the mechanism of full frame CCD smear, the cause of forming smear is analyzed theoretically. Combining with the actual engineering demand of detecting space targets, it puts forward a method of removing vertical smear of stellar targets and gradient smear of space targets. Finally the efficiency and real-time performance are proved with the measured image data and hardware platform