The　vertical　sections　of　Fe-12%　Cr-B-xAl-C　system　with　different　aluminum　contents　have　been　calculated　by　use　of　Thermo-Calc　software　and　the　influence　of　aluminum　content　on　the　phase　regions　and　the　parameters　of　eutectic　point　have　been　analyzed.　Fe-12.0%　Cr-1.0%　B-2.0%　Al-0.3%　C　and　Fe-12.0%　Cr-1.0%　B-4.0%　Al-0.3%　C　alloy　were　chosen　to　be　studied　by　experiment.　The　phase　transition　temperatures　were　measured　by　differential　scanning　calorimetry　and　the　microstructure　and　the　phase　type　was　detected　by　scanning　electrone　microscope-energy　dispersive　X-ray　spectroscopy　and　X-ray　diffraction.　The　results　indicate　that　calculated　phase　diagrams　agree　well　with　the　experimental　results　and　further　prove　the　thermodynamics　database　of　Thermo-Calc　software　is　reliable　and　it　can　be　used　to　help　design　the　alloy　composition　and　heat　treatment　process.