Fe-3.9 wt% B wear-resistant surfacing alloy with different Mn contents were prepared by plasma powder surfacing technology and influence of Mn element on crack resistance of Fe-B surfacing alloy was investigated. Based on the results, the primary phase changed from Fe2B to Mn2B with the addition of ferromanganese powder, but the morphology of the block structure hardly changed. Because Mn element belongs to a stable austenitizing element, it expands the austenite phase region and hinders the transformation of matrix γ-Fe to α-Fe. The eutectic structure change from fishbone-like, strip-like and honeycomb-like Fe2B+ α-Fe to small block structure Mn2B+ γ-Fe with better crack resistance. The addition of Mn element improves the hardness and wear resistance of the surfacing alloy layer. The hardness can reach 61.38 HRC, and the maximum wear resistance can be increased by 1.33 times compared with the sample without Mn element. The addition of ferromanganese powder can improve the toughness of the surfacing alloy layer while increasing the hardness and wear resistance. It provides an effective way to reduce the brittleness of the high boron iron-based wear-resistant surfacing alloy layer and improve its performance.