Abstract: To improve the erosion resistance of the steel, FeCoCrNiB_0.2Mo_x High-entropy alloy coatings were prepared on Q235 steel by laser cladding. An optical microscope was used for structure observation. The phase composition and lattice distortion of the coatings were studied by XRD. The effect of Mo on hardness and erosion resistance were discussed. The results show that: The FeCoCrNiB_0.2Mo_x coatings were composed of dendrites, and fine-grained regions can be observed between the layers. Because the higher cooling rate of laser cladding results an inhibition of the precipitation of intermetallic compounds, the FeCoCrNiB_0.2Mo_x coatings are completely composed of single-phase BCC solid solution. An erosion rate below 2.25 × 10⁻⁴ g/h suggested that the FeCoCrNiB_0.2Mo_x high-entropy coatings present a good performance on erosion resistance due to its high hardness which was higher than 600 HV0.2. And with the rise of Mo content, the lattice distortion of the coating becomes more severe, which leading to an increasing on hardness, and improvement of erosion resistance. Meanwhile, the slurry erosion mechanism of the FeCoCrNiB_0.2Mo_x high-entropy coatings is micro-cutting and forging extrusion.