This paper proposed to increase the number of co-frequency beams (CFBs) to reduce the positioning error (PE) in single-satellite interference source (IS) positioning. The method of IS positioning was discussed based on the difference of the received gain of CFBs interfered by the IS. PE with different number of CFBs is theoretical derived and simulated in various situations, which can conclude that the geometric dilution of precision (GDOP) can be significantly reduced nearly one order of magnitude with more CFBs in the presence of gain error (GE) and beam center pointing error (BCPE).