The work aims to obtain the hardfacing alloy with excellent overall performance including mechanical property, corrosion resistance, wear resistance, etc., by adding rare earth oxide La2O3 into ultra-low carbon Cr19Ni10 stainless steel hardfacing alloy to refine the microstructure. Four kinds of stainless steel hardfacing alloys were prepared with ultra-low carbon Cr19Ni10 stainless steel electrode containing rare earth oxide La2O3. The elements and phase composition of hardfacing alloy layers were measured by X-ray fluorescence spectrum, infrared carbon-sulfur analyzer and X-ray diffraction analyzer. The microstructure and grain size of hardfacing alloy layers were observed and analyzed by metallographic microscope and grain size statistical software. The hardness and Young’s modulus were measured systematically by microvickers hardness tester and nano-indentation instrument. The corrosion resistance and wear resistance were investigated by electrochemical workstation and CSM friction wear tester, and the corresponding morphology as well as the size of wear marks was observed and measured by white light confocal microscope. The lattice mismatch relationships between La2O3/γ-Fe interface were calculated by Bramfitt two-dimensional lattice mismatch theory. When La2O3 additives were added into the hardfacing alloy layer, with the increase of La2O3 addition, the austenite grain in the hardfacing alloy layer was significantly refined. When the addition of La2O3 increases from 0wt% to 1.5wt%, the average austenite grain area was decreased from 400 μm2 to 210 μm2. The mechanical properties, corrosion resistance and wear resistance of La2O3 added hardfacing alloy layers were obviously improved. When the addition of La2O3 increases from 0wt% to 1.0wt%, the microhardness of hardfacing alloys increased from 180HV to 225HV and macroscopic hardness increased from 125HBS to 150HBS. Young’s modulus increased from about 186 GPa to 217 GPa. The corrosion potential increased from ?0.4 V to ?0.25 V. The abrasion depth was reduced from 50 μm to 10 μm. The 2D lattice mismatch between La2O3(001) and γ-Fe(110) was 8.7% (<12%), which indicated that La2O3 could act as a medium effective heterogeneous nucleated substrate of γ-Fe. Therefore, austenite grains in hardfacing alloy layers could be refined. La2O3 can effectively refine austenite grains, improve the mechanical properties of hardfacing alloys, and enhance their corrosion and wear resistance. Moreover, there is an optimal value of La2O3 addition, and the best comprehensive performance can be obtained when the La2O3 addition is 1.0wt.%.