LEO hazard space debris can present catastrophic danger to operational spacecraft, and the detection of the space debris is the first and most important step in the process of collision avoidance and elimination. The object signal of these debris is faint. Besides, its optical character is uncertain and will change momently because of its high velocity and unknown attitude, all of which will bring serious challenge to the detection and identification. For fulfilling the demand of surveillance in real time, identification, collision alarm and accurate orbit ascertain, it needs to design and develop a space-based optical observation system. This article aims at providing a reference to this system, which summarizes the main characters of typical detectors, such as charge-coupled devices, avalanche photodiodes, position readout photon-counting detectors. The observation ability of space-based optical observation system based on these different detectors to LEO hazard space debris was analyzed.