Space diversity technology is used to overcome the influence of turbulence on BER of receiving terminal in atmospheric optical communication.Optimal transmitters or/and receivers are selected from multiple transmitters and receivers to improve SNR and decreade BER. Simulation results show that when the turbulence is strong,considerable improvement in average BER by means of multiple transmitters or/and receivers than with the system of a transmitter and a receiver is achieved. The result also shows that the effect of the optimal selection is the same significance in atmospheric optical channel of log-normal distribution as in wireless channel of Rayleigh fading.