The geomagnetic field, sodium atomic collision and recoil can affect the number of return photons from sodium laser beacon at the sodium layer in mesosphere. The geomagnetic field can cause Larmor precession of sodium atoms and severely reduce the optical pumping when the long pulse and the continuous wave laser act on sodium atoms. Furthermore, the atomic collision can increase the average return photon flux on a certain extent, while recoil decreases it. In addition, downpumping easily causes optical pumping into transition saturation under lower light intensity. In order to get more return photons, repumping may be used to enhance the average return photon flux. The numerical simulation indicates that the laser with 16% repumping power can excite the number of return photons as 2.33 times of the signal\|frequency (D2a) laser.