Abstract: The gas permeation is one of inherent characteristics of solid materials and one of reasons effecting sealing performances of closed containers. The gas permeation of materials is one of main factors which lead to the pressure decay and vacuum loss in some containers. For example, the research tasks of near-space stratosphere airship and long-life spacecraft have put forward more strict requirements than before about the performances of lifetime, reliability and safety. The vacuum insulation product and vacuum electronic device need to obtain and maintain vacuum for a long time. A kind of measurement method of gas permeation rate is studied. In this method, the quadrupole mass spectrometer and hot cathode ionization gauge are used as the key measurement sensors, and the constant conductance method is used to measure the leakage and outgassing rate on the low pressure side of permeability sample. Based on the above principle, a new measuring device of micro-permeability for thin-film materials is developed. And the device performance and a type thin-film material are carried out. The experimental results show that the lower limit of micro-permeability is less than 1×10^-14m²/s, the H₂O and N₂ permeation quantity of typical high separation membrane for VIP(Vacuum Insulation Panel) industry are on the order of 10^-2g/(m²·d).