In order to improve the low efficiency and high labor cost of FGM surfacing, this paper adopts plasma surfacing technology and uses H13 steel powder as welding material to conduct surfacing test on hot work die steel base metal (5CrNiMo). The influence of welding current on weld depth, weld width, microstructure and crack sensitivity of surfacing layer was studied, and the forming mechanism of welding crack was discussed. Results show that the weld depth and weld width increase with the increase of welding current. The microstructure of the surfacing layer is composed of martensite, residual austenite and carbide. With the increase of welding current, the martensite dendrites in the middle of the surfacing layer become coarser gradually. During multilayer welding, the austenite content in the upper part of interlayer interface is obviously higher than that in the lower part. When the welding current changes, the crack sensitivity of H13 surfacing layer is large. When the welding current is 150A, the surfacing sample with fewer cracks can be obtained. The cracks in surfacing layer can be divided into stress induced cracks and defect induced cracks according to their forming mechanism. By means of plasma surfacing, fast surfacing of hot working die is realized, which provides guidance for plasma surfacing of filling hot working die.