Fe-Cr-B-C　hardfacing　alloys　were　deposited　by　flux-cored　wire　using　metal　active　gas　arc　welding　(MAG).　The　effect　of　boron　contents　on　the　microstructures　and　boride　morphologies　of　the　hardfacing　alloys　was　analyzed　by　optical　microscopy　(OM),　scanning　electron　microscopy　(SEM)　and　X-ray　diffraction　(XRD).　The　results　indicate　that　the　microstructures　of　Fe-12Cr-xB-0.1C　alloys　consist　of　ferrite,　austenite,　(Fe,　Cr)2B,　and　(Fe,　Cr)23(B,　C)6.　The　morphology　of　borides　transforms　from　the　discontinuous　network　to　continuous　network　gradually　with　boron　content　increasing　to　3%　(mass　fraction).　As　the　boron　content　is　higher　than　3%,　the　amount　of　massive　primary　(Fe,　Cr)2B　increases　with　the　increasing　of　boron　contents.　Meanwhile,　the　size　and　distributing　of　(Fe,　Cr)2B　become　more　homogeneous.　The　morphology　of　primary　boride　has　many　kinds　of　distribution　shape,　including　massive,　strip,　fish-bone-like,　honeycomb　and　chrysanthemum.　The　shape　of　the　primary　(Fe,　Cr)2B　is　quadrangular　column　which　tends　to　grow　perpendicular　to　the　overlayer　surfaces.　Increasing　boron　content　can　significantly　improve　the　hardness　and　abrasive　wear　resistance　of　Fe-Cr-B-C　hardfacing　alloys　when　the　boron　content　is　lower　than　4%.