A　novel　micromechanical　model　is　developed　to　investigate　the　effective　elastic　properties　of　porous　materials　with　saturated　fluid.　In　the　present　model,　the　fluid　is　replaced　by　the　solid　material　through　applying　an　eigenstrain　in　the　domain　occupied　by　the　fluid.　Then　Young＇s　modulus　and　Poisson　ratio　of　the　composite　are　calculated　by　using　two-scale　expansion　method.　It　is　indicated　that　the　pore　fraction　of　microstructure　directly　influences　the　Young＇s　modulus　and　the　ability　to　resist　deformation.　Existence　of　the　fluid　can　dramatically　enhance　effective　properties　of　porous　materials.