The light intensity distribution of Fresnel circular aperture diffraction is analyzed theoretically，and the experimental equipment of Fresnel and Fraunhofer diffractions are set up． The experimental results show that Fraunhofer diffraction with circular aperture can be regarded as a special case of Fresnel diffraction． In other words，with the increase of the distance between the diffraction object-circular hole and the observation screen，the diffraction pattern transitions from Near-Field to Far-Field diffraction under the premise that the distance between the circular hole of the diffraction object and the observation screen remains unchanged．