Abstract: In order to meet the demands of space debris detection and precise orbit determination, by using high sensitive laser detection method with photon counting and the principle of photon counting detection of avalanche detector based on Geiger mode, space-based photon counting detection model was established on the relative radial velocity of detector and space debris. After theoretical analysis and simulation verification of photon counting laser detection of space debris, the results show that photon counting laser detection can effectively detect space debris(size of 10cm) and the average ranging error is 34.72cm. Its ranging accuracy could be improved 3 orders of magnitude compared with world traditional ground-based radar and photon-electronic technology. It can effectively reduce collision probability of spacecraft.