The　reaction　between　salt　fluxes　containing　metal　fluorides　and　main　elements　in　A356　alloy　was　investigated　by　thermodynamics　analysis　and　experiments,　and　its　influence　on　microstructure　and　constituent　of　Al　alloy　and　the　phase　of　fluxes　were　analyzed　by　SEM,　EDS　and　XRD.　The　results　reveal　that　the　equilibrium　constants　of　displacement　reactions　between　main　elements　of　A356　alloy　and　metal　chlorides　are　mostly　lower　than　those　of　metal　fluorides,　which　indicate　that　metal　chlorides　are　more　stable　than　fluorides　in　salt　fluxes.　NaF,　SrF2　and　BaF2　in　the　fluxes　can　react　easily　with　Al　or　Mg　and　generate　the　divorced　atoms　in　Al　melt,　such　as　Na,　Sr,　Ba,　to　modify　eutectic　silicon　significantly.　Na3AlF6　fluxes　can　also　react　with　Al　and　generate　trace　the　divorced　Na　atoms　to　modify　eutectic　silicon　slightly.　However,　influences　of　AlF3,　MgF2　and　CaF2　on　microstructures　of　A356　alloy　can　be　ignored.　Metal　fluorides　not　exhibit　measurable　effects　on　the　phase　of　salt　fluxes　while　NaF　and　BaF2　can　generate　new　phases　KMgF3　and　BaFCl　in　salt　fluxes,　respectively.　MgF2,　CaF2,　SrF2,　BaF2　would　remain　in　A356　alloy　because　of　their　high　densities　and　melting　points,　which　could　affect　the　constituents　of　alloy.　©　2017,　Journal　Office　of　Special　Casting　and　Nonferrous　Alloys.　All　right　reserved.