Hypoeutectic　Fe-Cr-B-C　hardfacing　alloys　with　different　molybdenum　(Mo)　contents　(The　design　content　was　0,　2,　3.3　and　4.5wt.%,　respectively)　were　deposited　using　the　flux-cored　wire　by　means　of　metal　active　gas　arc　welding.　The　effects　of　Mo　on　the　refinement　of　microstructures,　eutectic　microstructure　changes　and　improvement　of　wear　resistance　were　investigated.　The　main　results　were　shown　as　follows:　the　added　Mo　could　increase　the　volume　fraction　of　eutectic　microstructure　and　reduce　the　size　of　coarse　primary　austenite　as　well　as　the　volume　fraction.　The　carboboride　of　M3(B,C)　could　be　observed　in　hypoeutectic　Fe-Cr-B-C　hardfacing　alloys　at　the　Mo　design　content　of　≤2.0　wt.%,　while　that　of　M23(B,C)6　was　formed　when　3.3　wt.%　Mo　was　added.　Additionally,　the　wear　resistance　of　alloys　was　increased　with　the　increase　in　Mo　content.　Specifically,　the　highest　wear　resistance　of　alloys　was　achieved　at　4.5wt.%　Mo　design　content,　which　was　113.7%　higher　than　that　in　alloys　without　Mo.　Copyright:　©　2018　Editorial　Board　of　CHINA　WELDING.