Abstract: Three WC-10Co-4Cr coatings with different microstructure were prepared on 0Cr13Ni5Mo stainless steel by high velocity oxy-fuel/air-fuel (HVOF/AC-HVAF) thermal spray systems. The erosion behavior and mechanisms of three WC-10Co-4Cr coatings and 0Cr13Ni5Mo were investigated using slurry pot erosion equipment, and the relation between microstructure and erosion resistance of coatings was analyzed. The results indicated that the erosion resistance of three coatings was better than that of 0Cr13Ni5Mo. The erosion mass loss of three coatings was 6% ~ 35% of the 0Cr13Ni5Mo. The coatings with more homogeneous microstructure behaved better erosion resistance. For coatings, the dominant erosion mechanism was removal of binder and WC cuboids pull out at shallow impingement angle while coatings spallation mechanism dominated at high impingement angle. In contrast, micro-cutting mechanism dominated at shallow impingement angle while its dominant erosion mechanism was repeated deformation which resulted in the removal of materials at high impingement angle for 0Cr13Ni5Mo stainless steel. The erosion behavior and mechanisms of coatings at different test condition were dependent on their microstructure.