Geiger-mode avalanche photodiodes (G-APD) arrays is being concerned in ultra-weak-light detection. It is necessary to analyze performance of satellite laser ranging system based on G-APDs before engineering application. In this paper, the way of numerical calculation and simulation is used. In the condition of laser echo in the magnitude of single photon and only considering the dark counting noise, although the detect probability and the degree of identifying detection data are low, the effective detection points are enhanced relative to using a single photon detector. As laser echo in multiphoton and only considering the dark counting noise，the use of G-APDs is able to reduce the output of the detector drift. The laser echo is flooded when the detector working in geiger mode because of the strong noise which contains the dark counting noise and day light noise. The flooding effect is restrained by using G-APDs.