In order to test the reliability and performance of a flexiblewall permeameter (FWP), comparative tests of a FWP and a fallinghead permeameter were conducted with cementsoil samples, cement slurry samples, and soil samples, and comparative tests of different seepage pressures and sample heights and diameters were conducted for the FWP. The test results show that the FWP can provide accurate results, a reliable performance, and airproofed flexible walls, and it does not have strict requirements for sample preparation, which enable us to freely select the height and diameter of samples within a certain range. Permeability test with the FWP can be quickly finished using highseepage pressures. The FWP can be used to test cementsoil, cement slurry, and plastic concrete samples with permeability coefficients less than 1×10^-5cm／s and hard soil samples with permeability coefficients less than 1×10^-6cm／s.