In this work, a simple fabrication method of germanium-based metasurfaces is proposed, where the deposited Al2O3 layer with a high selectivity is chosen as the hard mask and retained after the dry etching process. The simulation and experimental characterization results verify the feasibility of the fabrication method. The experimental study on the fabrication methods of germanium-based metasurfaces is very significant as the meta-atoms with a higher refractive index can achieve 0 to 2π transmission phase variation with a smaller period under the same thickness-to-period ratio, which is consistent with the requirement of the period miniaturization in some cases.