Two　methods　were　used　to　control　the　size　of　in-situ　synthesized　NbC　in　Fe-Cr-B-C-Nb　hardfacing　alloy.　The　size　of　carbide　in　four　kinds　of　Fe-Cr-B-C-Nb　hardfacing　alloys,　with　niobium　content　of　2.2%,　3.2%,　3.9%,　and　5.0%,　respectively,　were　studied　in　this　paper.　A　new　kind　of　wear-resistant　alloy,　with　dispersed　micro/submicron　NbC,　was　in-situ　synthesized　by　plasma　cladding.　The　results　show　that　the　size　of　NbC　could　be　controlled,　and　increasing　niobium　content　increased　the　size　of　in-situ　synthesized　NbC,　and　the　carbide　tended　to　agglomerate.　The　cooling　conditions　played　an　important　role　in　controlling　the　size　of　carbide.　The　size　of　NbC　decreased　with　water　cooling,　but　would　increase　when　the　cooling　rate　decreased.