为了实现单光子测距系统的最佳性能接收，积分时间一定，分别研究激光功率对该系统的信噪比和距离精度的影响。首先，基于单光子探测机理，引入雪崩触发概率到固定频率的多脉冲累计探测系统线性信噪比模型中，蒙特卡洛仿真和理论模拟一致验证随着激光发送功率的增大，信噪比先增大再趋于稳定数值。其次，建立距离值的方差理论模型，蒙特卡洛仿真研究随着激光功率的增大，距离值精度提高并且趋于稳定数值，死时间增大可降低时间记录点的方差。实验结果表明，在积分时间50 ms和高背景噪声下，发射功率400 μW左右信噪比可达到最大值，距离精度可达到6 mm的最优值。最终，理论和实验共同验证该系统可以实现单光子测距系统的信噪比和距离精度的最佳性能接收。

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.