In the practical application of laser, the beam shaping is often needed to better meet the actual needs, for this purpose, firstly the analytical formula for diffraction transformation of Gaussian beam through micro-circular aperture is derived from the Kirchhoff diffraction formula, then three kinds of shaping transformations of Gaussian beam through micro-circular aperture are analyzed and discussed, the three cases of shaping transformations of Gaussian beam through micro-circular aperture are simulated with the Mtalab software. The simulation experiment shows that the analytical formula is reliable and the three kinds of shaping transformations of Gaussian beam through micro-circular aperture circular are feasible, which can be used in the laser beam control of laser engineering, micro-optics and MOEMS (Micro-Optical-Electrical-Mechanica-System).