We study the communication capabilities of a bi-directional real-time communication system that employs superconducting nanowire single-photon detectors (SNSPDs) under ultra low received optical power conditions. Furthermore, we analyze the influence of received optical power jitter on the system’s communication performance. To accomplish this, we construct a bi-directional real-time fiber optic communication system based on SNSPDs using the pulse position modulation. We successfully achieve bi-directional real-time video communication even under very low received optical power conditions, maintaining an average received optical power level of −75 dBm. The bit error rates for the uplink and downlink are measured at 2.56×10−5 and 3.08×10−5, respectively. Additionally, our investigation reveals that the SNSPD can tolerate a jitter range of up to 5 dB in received optical power while ensuring uninterrupted communication. This paper delves into the practical engineering application of a high-sensitivity optical communication system based on SNSPDs, offering novel insights for optimizing their future use in free space optical communication systems.