To explore the applicability of modeling on fuzzy sub-cluster in the pore structure of porous materials, aiming at theuncertainty of the pore structure of hardened gypsum,and according to particular property of the fuzzy sub-cluster in the multilayer, fuzziness and most probable pore, the relationship between its and the porosity, pore size distribution and most probable pore for building hardened gypsum are analysed. The porosity of hardened gypsum at different water／gypsum ratio is measured by using bulk density and the pore size distribution and most probable pore of hardened gypsum at different water／gypsum ratio has been experimented by adopting nitrogen adsorption porosimeter and mercury porosimeter respectively. The result shows whatever you use nitrogen adsorption porosimeter or mercury porosimeter, based on test of most probable pore, the competitive parameters about large or small pore size of hardened gypsum at different water／gypsum ratio are obtained by employing fuzzy sub-cluster.For porous materials, complicated pore structure may bequalitative or quantitative analysis by means of fuzzy sub-cluster so that study of the effect porous material on the thermal and moisture transfer.