To demonstrate the feasibility of space-borne applications of single-photon imaging technology, this study analyzes the elimination of the backscattering effect in the optical system, suppression of the single-photon avalanche photoelectric detection noise, and the free running mode. Next, the space-borne single-photon counting imaging system is modeled using a heavy tailed pulse laser function and the Monte Carlo method. The echo photon counting results are simulated for different conditions of orbit altitude, replication number, and gate number. The results show that the echo photon counting waveform is similar to the transmission waveform, as observed in reality. Single-photon imaging is possible within a certain distance threshold. Detections are missed when the replication number is lower than the gate number. The range accuracy can reach 0.09 m when the replication and gate numbers are both set to 2000 at an orbit altitude of 500 km based on the parameter set in this study. The methods in this paper provide technical support for the index allocation and on-orbit parameter adjustment of a space-borne single-photon counting imaging system.