以多像素光子计数器（MPPC）的光电特性和实验结果为基础，通过对传统的工作在线性模式下的雪崩光电二极管的信噪比公式进行修正，得到了适用于MPPC的信噪比表达式。对在随机光子探测模式下的信噪比表达式进行了数值计算和实验验证。数值模拟结果显示在随机光子照射下，最小可探测光子通量的量级为103 count/s, 最小可探测功率量级为10-15 W。对短脉冲光子探测模式下的光子计数信噪比表达式进行了数值分析，结果显示，利用调节合适的光电子数等效阈值进行光子计数的方法能够大大提高探测器的信噪比，该方法相比于传统的光子探测器有明显而独特的优势，在短脉冲弱光探测的场合，诸如脉冲激光测距、高能粒子物理等方面有较大的应用前景。

The signal-to-noise ratio formulas of a multi-pixel photon counter (MPPC) are obtained based on its photoelectric characteristic and experimental results, and by revising the traditional signal-to-noise ratio (RSN) formula of linear mode avalanche photodiode (APD). The method is used for random photon detection mode and short-pulse photon detection mode, respectively. The numerical calculation results using the obtained RSN formula are consistent with the experimental results. The numerical results show that the minimum detectable photon flux is of the order of 103 count·s-1, the minimum detectable power is about 10-15 W. Numerical analysis for the RSN formula of the short pulse photon detection mode is done. The results show that the RSN of the MPPC can be obviously improved by adjusting the photoelectron-number equivalent threshold of the MPPC. This method of the MPPC has its own advantage compared with the traditional photon detector. It has wide application prospect in the field of pulsed low-level light detection such as pulsed laser ranging and high-energy particle physics.