Abstract: The difference between the traditional boiling method and the caliper method used for testing of dense ceramic materials density and porosity was compared. The results show that the caliper method could make up shortcomings existing in the traditional boiling method to reduce the impact of personal and environmental fators on testing data and to improve the stability of testing results. Meanwhile, through extending Archimedes formula, it could be proved that the open porosity, closed porosity and true porosity of the dense ceramic materials were dependent on their own densities, including the bulk density, the apparent density and the true density.