Avalanche photodiode multiplication factor and noise are affected by temperature. In the constant false alarm,APD multiplication factor and noise will interact. In order to study the influence of temperature change on APD performance and evaluate it,the influence of temperature on dark current,thermal noise,multiplication factor and constant false alarm compensation working principle are analyzed. The relationship model between temperature and multiplication factor under constant false alarm is established. The model is verified by experiments. The influence of temperature on multiplication factor under different background light and different false alarm probability is analyzed. An evaluation method for the influence of temperature on the performance of APD under constant false alarm is proposed. The results show that under the constant false alarm,the multiplication factor decreases with the increase of temperature;at the same temperature,the stronger the background light or the smaller the multiplication factor,the lower the false alarm probability and the smaller the multiplication factor. The weaker the background light and the lower the false alarm rate,the more obvious the effect of temperature on the multiplication factor.