The synchrotron radiation (SR) stimulated etching of SiO2 thin film surface was investigated with a contact cobalt mask, and the etched pattern of SiO2 thin films on silicon was made. The SiO2 thin film was grown on silicon surface by thermal oxidation. The contact cobalt mask was fabricated on SiO2 thin film by combining the techniques of photolithography and RF-magnetron sputtering. In the experiment, the anisotropic etching of SiO2 was effectively achieved by SR radiation with SF6 as the reaction gas. The etching rate increased with increasing gas pressure of SF6 in a certain range, and with decreasing the substrate temperature. Under SR irradiation with flowing SF6 and O2 did not etch the silicon crystal and the etching stopped completely at the SiO2/Si interface. Furthermore, the Co provided high resistance against the SR etching, indicating that Co is an ideal mask material for the synchrotron radiation stimulated etching.