Abstract:Single Photon Detector(SPD) is a kind of instrument with ultra-low noise and extremely high sensitivity. It is able to detect and count the smallest energy quantum-photon, to realize the detection of weak signal. Superconducting Nanowire Single Photon Detector(SNSPD) is one of new type SPDs, which has many advantages over traditional SPD, including high count rate, low dark counts and so on. However, it is only when SNSPD runs at critical state on bias mode and works with many other modules that could trigger hotspot effect. In this paper, a bias power supply system is designed for the experimental system of SNSPD based on superconducting characteristics of NbN, coupled with functions of temperature control and signal conditioning. Experiment shows that stable parallel constant current biases can be output from four channels with a precision of 0.1 μA, a range from 0 to 99.9 μA, and temperature precision of 0.05 K; and pulses generated by hotspot effect are regulated through signal conditioning and then detected successfully by analytical instrument, which can meet the requirements of single photon detection.