In　this　study,　the　cement　paste　corroded　in　sodium　sulfate　solution　was　regarded　as　a　three-phase　composites　composing　of　unhydrated　cement　particles,　reaction　products　and　pores　on　meso-scale.　First　of　all,　based　on　the　results　of　the　in-situ　X-ray　Computed　Tomography　(X-ray　CT)　test,　a　three-dimensional　(3D)　meso-scale　finite　element　(FE)　model　of　the　cement　paste　specimen　was　established.　Subsequently,　homogenization　methods　were　used　to　calibrate　the　mechanical　parameters　(elastic　modulus,　Poisson＇s　ratio　and　strength)　of　the　model　and　the　constitutive　relations　of　unhydrated　cement　particles　and　reaction　products　were　modified.　Finally,　the　failure　process　of　the　cement　paste　specimens　conducted　by　the　uniaxial　compression　test　was　simulated.　The　results　showed　that　the　compressive　strength　of　the　cement　paste　specimens　experienced　a　process　of　increasing　first　and　then　decreasing　with　the　increase　of　corrosion　time,　caused　by　the　combination　of　cement　hydration　and　sulfate　ion　corrosion.　Additionally,　the　simulation　results　and　the　uniaxial　compression　test　results　were　in　good　agreement,　indicating　that　the　modified　constitutive　relations　were　effective　and　the　3D　meso-scale　numerical　simulation　can　well　predict　the　uniaxial　compression　test　of　cement　paste　specimen　under　the　corrosion　of　sodium　sulfate.　(C)　2019　Elsevier　Ltd.　All　rights　reserved.