Abstract: The passive quenching method is used to characterize InGaAs/InP avalanche photodiode (APD) operating in Geiger mode. Based on the feature that the voltages of APD terminals tend to be stabilized after avalanche, a new passive quenching method is put forward to determine dark breakdown voltage. The experiment indicated, with the decrease of the temperature, the optimum operating area of APD became wider, the optimum gain of APD was increased, and APD’s sensitivity was improved. By comparing the dark current and the signaltonoise ratio of EGG with those of Epitaxy APD, it is discovered that Epitaxy APD is preferable for single photon detection due to its low noise level and high signaltonoise ratio. The study on characteristics of different APDs is helpful to choose proper type of single photon detector for quantum communication.