The laser echo signal will cover the certain range while laser ranging to space targets through transmitting laser signal from the ground station. The number of laser echoes per unit time will be obviously increased through utilizing multi-telescopes to receive signal on ground. It′s very helpful to enhance the detection ability of measuring space targets for laser ranging system. According to laser ranging link equation and the theory of signal detecting probability, the analysis of the effect on the detecting probability of laser ranging system with multi-telescopes to receive laser signal was performed to research on the equivalent receiving ability. Based on the 1.56 m aperture of astronomical telescope about 60 m far from the 60 cm telescope at Shanghai Astronomical Observatory, Chinese Academy of Sciences, the activity of laser ranging to artificial satellites with retro-reflector was implemented to research on the detecting ability of dual-telescopes while simultaneously receiving laser echo signal. The number of laser echoes had increased by 4 to 5 times compared with the aperture of 60 cm telescope system. The effect on increasing the detecting ability of measuring space targets was obvious. Considering the laser measuring ability of 1.56 m telescope system, the equivalent receiving aperture of 1.61 m can be derived for 1.56 m/60 cm telescopes. The analysis on the detection ability of laser ranging to space targets with the orbit height of 1 000 km and the size of 10 cm and number of receiving telescopes were also performed. From the experiments the technical feasibility and advantage of multi-telescopes to receive signal are validated, which will play an important role in the weak signal detection and laser ranging in future.