Abstract: Porosity is one of the important parameters in the research and use of materials. The porosity of different materials plays different roles. The porosity testing methods of irregular wettable and non-wettable bulk and powder materials were investigated by the gas expansion replacement method and vibration stacking method. The experimental results showed that the appearance volume test result of irregular wettable materials by the gas expansion replacement method was consistent with the test results by the fluid displaced method. So the appearance volume test bottleneck of irregular wettable materials was solved by the gas expansion replacement method. The approximate appearance volume of the powder samples with a small particle size was tested by the vibration stacking method, solving the problem that the appearance volume of powder samples cannot be tested. Based on the ideal gas state equation, the true volumes of irregular wettable and non-wettable bulk and powder materials were calculated by testing the pressure values of two known volume sample compartments, respectively. A method for calculating the porosity of the materials was established by dividing the true volume by the exterior volume, calculating the percentage after subtracting the internal pores of the material and the pores between the particles, that is the percentage of non-pores, and then subtract the percentage of non-pores by 100%, thus establishing the calculation method of the porosity of the material.