BER measures the accuracy of data transmission within specified time,which is an important parameter to evaluate the performance of communication system. First,this paper analyzes the influence factors of BER for DPSK self-homodyning coherent detection system such as modulation format, atmospheric turbulence, coherent demodulation. We take it into consideration that atmospheric channel will affect the transmission signal ,simulated the DPSK self-coherent detection system in different weather conditions and analyzed the results. The simulation results shows that the bit error rate of 10 Gb/s self-coherent detection system reaches 10-10 ,when the weather condition is light haze. It indicates that self-coherent detection system has great potential in satellite-ground laser communication.