Concrete　is　a　typical　porous　medium　permeated　by　an　interconnected　network　of　pores　which　have　great　influences　on　elastic　modulus,　strength　and　other　mechanical　parameters　of　concrete　across　both　micro　and　macro　scale.　Concrete　was　considered　as　a　three-phase　composite　with　aggregates,　pores　and　mortar　matrix.　Pores,　micro　crack,　micro　flaw　and　aggregates　were　put　into　the　mortar　matrix　randomly　by　the　Monte　Carlo　simulation　method,　and　the　effective　mechanical　properties　of　porous　material　was　derived　according　to　the　three-phase　sphere　model　and　hollow　cylindrical　rod　model.　Then　the　effective　constitutive　model　of　porous　material　was　established,　and　finally　the　meso　element　equivalent　model　of　porous　concrete　specimen　was　built.　Thus　two-grade　porous　concrete　specimen　in　uniaxial　tensile　and　compression　was　analyzed　by　means　of　nonlinear　method.　The　results　indicated　that　the　existence　of　pores　and　micro　cracks　had　great　influence　on　macro　elastic　modulus,　strength　and　residual　strength　of　concrete,　which　should　not　be　neglected　when　analyzing　the　macro-mechanical　properties　and　damage　fracture　of　concrete.