Introduction:　In　our　study,　various　test　methods　were　adopted　to　explore　the　mineralogical　characteristics,　grindability,　particle　morphology,　particle　size　distribution,　and　environmental　leaching　toxicity　of　iron　ore　tailings　(lOTs).Methods:　The　methods　include　petrographic　analysis,　X-ray　diffraction　(XRD),　scanning　electronic　microscopy　(SEM),　synchronous　thermal　analyzer　(DSC-TGA),　electron　probe　X-ray　microanalyser　(EPMA),　and　synthetic　precipitation　leaching　Procedure　(SPLP).Results:　The　results　show　that　the　used　IOTs　contained　14.54%　iron　which　was　mainly　stored　in　magnetite　and　pyrite.　The　content　of　iron　silicate　accounted　for　11.82%　of　the　total　iron　content.　Most　of　it　existed　in　silicate　minerals,　including　grunerite　and　hornblende.　A　small　amount　of　iron　was　contained　in　biotite,　chlorite　and　augite.　Besides,　the　grindability　of　lOTs　was　much　better　than　that　of　granulated　blast　furnace　slag　(GBFS).　After　grinding　for　140　min,　the　mass　fraction　of　lOTs　particles　with　the　particle　size　less　than　5　um　was　44.19%.　These　particles　could　be　used　to　fill　in　the　voids　in　the　cement-powder-packed　structure.　lOTs　also　contained　a　large　number　of　submicron　and　nanoscale　particles.Discussion:　With　great　strength　and　environmental　friendliness,　the　composite　cementitious　material　(CCM)　prepared　from　lOTs　can　be　well　applied　to　the　building　material　field　and　environmental　remediation.