Iron　oxide　catalysts　which　were　used　in　gaseous　2,5-dimethylphenol　(2,5-DMP)　alkylation　with　methanol　was　modified　by　Sn,　Si　and　K　to　produce　2,3,6-trimethylphenol　(2,3,6-TMP).　Characterized　by　FE-SEM,　ICP-OES,　XRD,　Raman,　in-situ　FT-IR,　N-2-adsorption/desorption,　XPS,　FE-TEM　and　NH3-TPD.　The　primary　surface　segregated　SnO2　nanocrystals　and　the　amorphous　Si-containing　coordination　structures　which　were　formed　on　non-activated　catalyst　limited　the　growth　of　hematite　grains;　catalysts　activation　triggered　by　vapor　methanol　successfully　formed　a　surface　Si-Fe-Sn　ternary　co-solution　structure　through　lattice　oxygen　consumption　and　migration,　which　passivated　the　uniformity　of　grains　and　blocked　the　direct　contact　between　them;　K　was　used　to　weaken　the　acidity　of　undesirable　strong　acid　sites.　The　main　product　was　proved　to　be　2,3,6-TMP　by　H-1　NMR,　which　is　a　synthetic　intermediate　of　vitamin　E　with　high　value.　The　best　2,5-DMP　conversion　and　2,3,6-TMP　selectivity　can　reach　99.25%　and　100%　under　the　condition　of　370　degrees　C　and　1.5　h(-1)　LHSV,　respectively.　Compared　with　traditional　iron　oxide　catalysts,　the　undesirable　sintering　has　been　reduced　by　23.2%　and　2,3,6-TMP　productivity　is　1.5　times　that　of　the　reference　data　because　of　this　structure.　This　work　provides　a　good　reference　for　the　improvement　of　other　iron-based　materials　used　in　complex　reductive　atmosphere.