The efficiency of a laser ranging system directly influences its ranging capability, necessitating a reliable method for testing system efficiency. We present a testing method that assesses the efficiency of a laser ranging system using only standard stars, without the need for additional equipment. The approach leverages the capabilities of single photon detectors and measuring photon flux from stars at varying zenith angles, the impact of atmospheric extinction on system efficiency is considered. Through this method, the reception efficiency of the laser ranging system at TianQin station was tested and compared with the measured values of mirror reflectance, ensuring the requirements for performance monitoring of the laser ranging system.