When a partially coherent beam is transmitted in turbulent atmosphere channel, the optical intensity scintillation effect caused by atmospheric turbulence can be effectively suppressed, and accordingly performance of communication link is improved. According to Gamma-Gamma atmospheric channel model and characteristics of partially coherent beams, the analytic expressions of average bit error rate(BER), outage probability and average channel capacity were obtained for partially coherent optical communication system. Based on these results, the influence of spatial coherence length and communication distance on performance of communication link was analyzed. Numerical results show that as the spatial coherence length of a partially coherent beam decreases, the system BER and outage probability decrease gradually under the same atmospheric turbulence conditions and transmission distance, and the outage probability is lower than 10-6 and system BER is 10-5, when average signal-to-noise ratio (SNR) is 30 dB; Meanwhile, as the spatial coherence length of the partially coherent beam decreases, average channel capacity of the system increases, and the average channel capacity is up to 3.8 b/s·Hz-1 when SNR is 12 dB. The analytical results provide a theoretical basis for the realization of the communication of partially coherent light in the turbulent atmosphere.