Buildings　in　coastal　areas　have　been　suffered　from　seawater　immersion　and　tidal　erosion　for　a　long　time,　and　the　resistance　of　building　structures　to　sulfate　erosion　has　always　been　a　concern.　In　order　to　solve　this　problem,　this　paper　attempts　to　develop　a　new　low-carbon　green　geopolymer　cementitious　material　that　is　resistant　to　sulfate　attack.　The　effect　of　this　geopolymer　material　on　sulfate　erosion　resistance　is　investigated　in　terms　of　alkali　admixture,　alkali　modulus,　water-binder　ratio　and　fly　ash　admixture.　In　this　paper,　the　geopolymer　materials　were　tested　for　sulfate　erosion　resistance　by　dry-wet　cycle　sulfate　erosion　mechanism.　It　was　shown　that　the　contribution　in　improving　the　resistance　of　geopolymer　materials　to　MgSO4　attack　can　be　ranked　as　follows:　water-binder　ratio　＞　fly　ash　content　＞　alkali　content　＞　alkali　modulus;　Increasing　alkali　admixture,　water-binder　ratio　and　fly　ash　admixture　and　decreasing　alkali　modulus　will　promote　the　generation　of　gypsum　in　the　specimen;　Mg2+　in　MgSO4　solution　makes　the　volcanic　ash　reaction　products　decalcify,　and　the　free　Ca2+　and　[SO4](2-)　combine　to　generate　gypsum,　causing　gypsum-type　erosion　damage　in　the　specimen.