The invention discloses a photon number resolution enhanced laser communication system and method. The system comprises a controller, a waveform generator, a pulse laser source, an adjustable attenuator, an array superconducting nanowire single-photon detector, a power amplifier, a power synthesizer, an analog-to-digital converter and an oscilloscope, wherein the controller carries out code modulation on data needing to be output and inputs the data to a waveform generator, the waveform generator converts the coded information into an electric pulse signal and outputs the electric pulse signalto the pulse laser source, the pulse laser source generates a corresponding optical pulse signal according to the input electric pulse signal, then the optical pulse signal is input into the array superconducting nanowire single-photon detector through the adjustable attenuator, a signal with photon number resolution is output through the power amplifier and the power synthesizer, and finally thesignal is received and collected by the oscilloscope after being shaped by the analog-to-digital converter. Error code interference caused by external optical space noise and dark noise of the superconducting detector is greatly reduced, so that the error rate is enabled to be close to the self-owned light quantum error code limit of optical communication.