Space-based space surveillance is the extension of ground-based system, and needs the high performance CCD as its imager. Development of scientific CCD is firstly reviewed, and the demands of space surveillance for CCD are analyzed. Electron multiplying CCD is the novel imager that has ultra-low readout noise and high quantum efficiency. The principle of EMCCD is later presented and CCD97 is introduced to space-based space surveillance. Several problems of EMCCD in space surveillance are discussed, such as the control of the multiplying gain, mosaic arrays technology, etc.