Abstract: From the Collins formula,the diffraction of Bessel-Gaussian beam passing through circular and annular apertures was studied based on numerical simulation.The results indicate that the axial intensity of Bessel-Gaussian beam through a circular aperture changes with the Fresnel number F periodically;the axial intensity of Bessel-Gaussian beam through an annular aperture attenuates with the F at the function of vibration.When F is the same,the transversal intensity of Bessel-Gaussian beam through a circular aperture distributes more smooth than an annular aperture.The smaller the annular aperture,more obvious is the modulation of transversal intensity;when the annular aperture is equal to the waist of the beam,the transversal intensity is independent of the Fresnel number F.