The　purpose　of　this　paper　is　to　present　a　quantitative　method　for　evaluating　the　engineering　geological　suitability　of　potential　sites　in　order　to　select　the　optimal　site　for　large-scale　infrastructure.　Based　on　the　fuzzy　comprehensive　evaluation　decision　method　and　analytic　hierarchy　process　(AHP),　an　engineering　geological　suitability　comprehensive　evaluation　index　(EGSCEI)　model　was　applied　in　the　selection　of　a　site　for　the　construction　of　the　China　Initiative　Accelerator-Driven　System　(CiADS)　and　the　High-Intensity　Heavy-Ion　Accelerator　Facility　(HIAF).　In　this　model,　seven　parameters,　including　land　use,　geomorphology,　geological　structure,　lithology,　hydrogeology,　geological　disaster　and　rock　weathering,　were　selected　as　the　evaluation　factors.　The　factor　evaluation　matrices　were　established,　and　the　weight　vector　of　the　seven　factors　was　determined　using　the　AHP.　The　engineering　geological　suitability　fuzzy　comprehensive　evaluation　vectors　were　then　computed.　Finally,　according　to　the　normalized　engineering　geological　suitability　comprehensive　evaluation　vectors　and　the　quantified　evaluation　ranking　vector,　the　EGSCEI　values　were　calculated.　As　a　result,　site　No.　3　was　evaluated　as　the　most　optimal　site　of　the　three　potential　sites　for　the　construction　of　the　CiADS　and　HIAF.　The　result　was　adopted　by　the　Chinese　government,　and　site　No.　3　became　the　selected　location.　This　case　study　shows　that　the　EGSCEI　model　is　scientific,　reasonable　and　applicable　in　providing　a　reference　for　similar　large-scale　infrastructure　site　selection.