The work aims to study the application of mask in the gas permeability test of materials, and evaluate the repeatability, accuracy and data stability of the test data. Five kinds of samples covering the barrier performance range of high barrier, medium barrier and low barrier were selected and tested by three masks with different areas and the original area of the instrument testing cavity and the repeatability, stability and accuracy of the test results were analyzed and evaluated. When the mask of 12.56 cm2 was used for the high barrier material PET sheet, relatively stable test results could be obtained, while when the masks of 1.77 cm2 and 5 cm2 were used, the relative standard deviation, relative range and test data deviation of the test results were poor. It was not recommended to use 1.77 cm2 and 5 cm2 masks for OTR test of the PET sheet. When KOP/CPP was tested with the mask of 1.77 cm2, both the relative standard deviation and the deviation of test data were slightly greater than 10%. When PET/CPP was tested with the mask of 1.77 cm2, the test data deviation was slightly greater than 10%. Good results could be obtained when BOPE/LDPE and TPU were tested with the mask of 1.77 cm2. Therefore, it can be concluded that mask is an excellent solution to solve the test difficulties of sample material characteristics, equipment range limitations, sample size, etc. For the permeability test of medium and low barrier materials, the test data with good reliability and stability can be obtained through application of mask. When the oxygen transmission rate is tested, a large test area should be selected as far as possible. Small area mask is not suitable for gas barrier test of high barrier materials.