This　article　creatively　established　a　four-stage　methodology　to　evaluate　the　macroscopic　elastic　modulus　of　the　cement　mortar　corroded　in　brine　solution.　At　first,　the　nanoindentation　technique　was　utilized　to　measure　the　microscopic　elastic　moduli　of　a　10　x　10　lattice　locating　on　a　region　containing　sand　aggregates,　cement　paste　and　interface　transition　zone　(ITZ).　The　compositions　and　contents　of　each　point　were　determined　by　XRD　combined　with　SEM-EDS.　Secondly,　three　different　thicknesses　(5　mu　m,　10　mu　m　and　15　mu　m)　of　the　ITZ　were　assumed　and　the　corresponding　microscopic　elastic　moduli　were　calculated　based　on　porosities　from　imaging　process,　multi-scale　homogenization　method　and　the　Voigt　parallel　mode.　The　thickness　of　the　corroded　ITZ　was　then　determined.　Moreover,　the　Lu　&　Torquato　model　was　used　to　calculate　the　volume　fractions　of　cement　matrix,　aggregates　and　ITZ　of　the　mortar,　treated　as　important　parameters　to　predict　the　macroscopic　elastic　moduli　of　corroded　and　non-corroded　mortar　with　homogenization　method.　Finally,　a　Reuss-Voigt　equivalent　approach　was　proposed　to　calculate　the　macroscopic　elastic　modulus　of　the　mortar,　which　showed　good　agreement　with　the　measured　macroscopic　elastic　modulus　from　uniaxial　compression　test.　Therefore,　the　methodology　utilized　to　evaluate　the　macroscopic　elastic　modulus　of　the　corroded　cement　mortar　is　effective.