Using extended Huygens-Fresnel principle,the propagation characteristics of the Gaussian beams limited by a circular aperture in atmospheric turbulence are analyzed,and the analytical expression of average intensity on axis is derived. Through the numerical simulation,the average intensity on axis is calculated with different turbulence intensity,aperture size and wavelength. The results shows that the oscillation rises in the near-field,its amplitude reduces with the increase of the turbulence intensity and transmitting aperture,and its period rises with the increase of propagation distance. In far-field,the oscillation dies out and the average intensity declines smooth with the increase of propagation distance,the position of the last maximum value of average intensity is in direct proportion to the turbulence intensity and wavelength,and is in inverse proportion to the transmitting aperture.