This　paper　aims　to　quantitatively　evaluate　the　elastic　modulus　of　concrete　through　microscopic　tests　and　a　multiscale　mechanical　homogenization　method　considering　interface　transition　zone　(ITZ).　The　mechanical　properties　tests　were　carried　out　for　concrete　samples　with　0%　or　10%　silica　fume.　The　elastic　modulus　and　volume　fraction　of　individual　phases　of　hardened　paste　and　elastic　modulus　and　thickness　of　the　ITZ　around　coarse　aggregate　were　obtained　by　a　series　of　microscopic　tests　and　theoretical　studies.　The　results　showed　that　the　incorporation　of　silica　fume　mainly　increased　the　elastic　modulus　and　volume　proportion　of　the　C-S-H　gel,　while　results　in　the　improvement　on　ITZ　elastic　modulus　and　reduction　on　its　thickness.　To　further　simulate　macroscopic　elastic　modulus,　the　concrete　was　divided　into　four　scales　ranging　from　nano　to　macro　and　a　model　was　established　by　homogenization　scheme　combining　Mori-Tanaka　(MT)　and　self-consistent　(SC).　The　influence　of　bond-slip　ITZ　model　or　homogeneous　ITZ　model　on　the　simulation　results　was　discussed　on　the　fourth　scale.　Moreover,　the　effects　of　the　nanoscopic　phases,　microscopic　phases　and　ITZ　properties　on　the　elastic　modulus　of　concrete　were　analyzed　to　confirm　the　essential　role　of　ITZ　in　the　elastic　deformation　analysis.