Abstract: Relationships between the formation pressure,time sustained, and the microporous parameter of polyimide porous materials are explored when they are made by the molding pressing process. Porous polyimides are made from powders of grain size of 20 μm, under the pressure of 35 to 105 MPa and sustained for 0 to 3 minutes. Its parameters are measured through foam diameter instrument. Power functions are observed between the pore size, porosity, permeability, permeability coefficient and the pressure. The distribution consistency of the micropores is found to be more dense in the case of sustained pressure. Process modes for making different porous materials having various properties are concluded.