Objective To develop novel hypereutectic Fe-Cr-C hardfacing alloys (Y2O3-free and Y2O3-modified, respectively) so as to improve the coarse carbides and increase the wear resistance of Fe-Cr-C hardfacing alloys. Methods The hardfacing alloys were deposited by the automatic open arc surfacing welding method. The microstructures were observed by optical microscopy. Meanwhile, the macro hardness of the hardfacing alloy surface was measured by the Rockwell hardness tester. The wear resistance of the hardfacing alloy surface was evaluated by the abrasive wear test. Worn morphology was observed by field emission scanning electron microscopy. Moreover, the mechanism of the microstructure refinement by the two-dimensional misfit theory was also discussed. Results The results showed that the microstructures of the hardfacing alloy consisted of the primary M7 C3(M = Cr, Fe) carbide and eutectic structure (eutectic M7 C3 carbide+ retained austenite and its product). The average size of primary carbide was about 22 μm. The mass loss and the hardness of the Y2 O3 -free alloy were 0. 85 mg / mm2 and 55HRC, respectively. After adding Y2 O3 , the average size of carbide was about 16 μm. The mass loss of the coating was 0. 59 mg / mm2 and the hardness was 57HRC. The two-dimensional lattice misfit between the face (001) of Y2 O3 and the face (100) of orthorhombic M7 C3 was 8. 59% . Conclusion By adding Y2 O3 as the heterogeneous nuclei, the primary M7 C3 carbide was refined and the wear resistance of the hypereu-tectic Fe-Cr-C hardfacing alloy surface can be improved.