In order to realize the best performance receiving ranging system based on single photon counting, based on the constant integration time, the system output SNR and range precision were studied with the increased laser power. First, the "arm probability" was introduced to the linear SNR model based on fixed frequency multi-pulse accumulation detection system. Monte Carlo simulation and theory simulation all proved that with the increased laser power, the SNR got larger and became stable. Then the range deviation model was settled, with the increased laser power, range precision enhanced and became stable by Monte Carlo simulation. Experimental results indicate that based on high background noise, the maximum of SNR can be obtained with emitting laser power at about 400 μW at 50 ms integrated time. Range precision reaches the optimal level at 6 mm. Finally, theory and experiment all prove that the optimal performance receiving of SNR and precision is achieved on single photon counting ranging system.