The　hydration　process　of　calcium　sulfoaluminate　(CSA)　and　aluminate　cement　(CAC)　is　influenced　by　their　composition　and　calcium　sulfate　sources.　Increasing　the　calcium　sulfate　content　promotes　ettringite　generation;　however,　exceeding　the　optimal　threshold　may　cause　volume　instability.　This　study　aims　to　optimize　sulfate　levels　in　CSA　and　CAC　by　adjusting　the　SO3/Al2O3　3　/Al　2　O　3　molar　ratios.　Contour　maps　were　used　to　analyze　how　different　sulfate　sources　and　calcium　sulfate　levels　affect　strength　development,　ettringite　formation,　and　volume　stability.　Both　gypsum　and　anhydrite　similarly　improved　compressive　strength　in　CAC　and　CSA　at　equivalent　SO3/Al2O3　3　/Al　2　O　3　ratios.　However,　gypsum　caused　more　significant　expansion　than　anhydrite　at　equivalent　SO3/　3　/　Al2O3　2　O　3　ratios,　as　indicated　by　the　higher　expansion　values　in　gypsum-rich　regions.　The　SO3/Al2O3　3　/Al　2　O　3　molar　ratio　is　crucial　for　regulating　ettringite　formation,　enhancing　compressive　strength,　and　ensuring　volume　stability　in　CSA　and　CAC　systems.　Maintaining　this　ratio　below　1.0　enabled　the　addition　of　sufficient　calcium　sulfate　to　achieve　optimal　performance.