Abstract: The stannum attenuation foil is fabricated by magnetron sputtering. The mass thickness of the stannum attenuation foil measured by a vacuum α energy spectrum mass thickness apparatus is 450.3 μg/cm 2, and the measurement result from α step 100 thickness measurement apparatus shows that the surface nonuniform is less than 3 %. The mass thickness and surface homogeneity of the stannum attenuation foil can meet the request of soft X ray laser experiment. The impurities and surface oxide of the stannum attenuation foil are studied through AES method, and combine with Ar ion beam etching, the depth distribution of oxygen is analyzed. The results indicate that there is an oxide layer on the surface of the stannum attenuation foil exposed in air environment, and the main components of the oxide layer are SnO 2 and Sn 2O 3.