In view of the problem that the outdoor visible light communication is influenced by the atmospheric turbulence, the influence of atmospheric turbulence and different weather conditions on the average time slot error rate(SER) of the visible light communication system under the Gamma-Gamma channel has been comprehensively analyzed by the generalized hypergeometric method. The simulation analysis shows that 16-order differential pulse position modulation(16DPPM) can effectively suppress the effects of turbulence, the average SER is significantly reduced by equal gain combined(EGC) reception merge receiving technique. Under the turbulence channel, the average SER of the 16DPPM based on single input multiple output system with three or four receiving antennas is significantly improved compared with the 16DPPM single input single output system when it is sunny, haze, mist and medium fog weather conditions.