This standard specifies the test method for the hydrophobic performance of porous hydrophobic membranes, including the determination of the water permeability pressure and the critical wetting value. It is suitable for separation membranes with a pore size range of 0.01 μm to 10.0 μm. This standard is applicable to hydrophobic membranes that maintain the gas or oil phase during the membrane separation process. It provides a unified test specification for the performance evaluation and quality control of membrane materials to ensure their Reliability in practical applications. This test method is widely used in the chemical, pharmaceutical and other membrane separation technology fields.