Abstract: In order to study the effect of Mo element on the microstructure and other properties of FeAlCuCrNiMo_x high entropy alloys, FeAlCuCrNiMo_x high entropy alloy powder was used as core flux wire and then surfaced on 45 steel plate with gas protection. The hardness, microstructure and corrosion resistance of the weld were analyzed The results showed that FeCuCrAlNiMo_x series high entropy alloy consist of single body centered cubic AlFe phase. When x=0.8, the structure of alloy surfacing layer was minimal, the grain boundary was obviously strengthened, the hardness of the alloy surfacing layer was the highest, the average hardness was 47.8 HRC, and the minimum wear amount was 0.08 g. The corrosion potential reduced after a certain amount of Mo element was added, this meant that the corrosion resistance was worse.