In satellite-ground laser communication system, atmospheric turbulence causes the fluctuation of the receiving optical signal, which can arouse burst bit error while in bad situation In order to study the characteristic and influence of the burst bit error, a new simulation method of fluctuated receiving signal simulation was studied in this paper, which uses the power series of Gaussian process to fit the target process The highest power order of Gaussian process was set to 3, and the factor of power series was obtained from the statistic character (mean, quadratic mean deviation, skewness and kurtosis) of the envelope fluctuation of the receiving optical signal, and the power spectra density of the fluctuation was fit by FFT /IFFT. This method takes advantages in computational complexity and resource consumption.