Laser-directed energy deposition technology can be used to achieve fixed-point repair and remanufacturing of die-casting molds. However, during the laser forming process of medium-carbon hot work die steels, such as H13 steel, high-carbon martensite with intrinsic brittleness is generated, leading to problems such as cracking and insufficient plasticity. In response, a small amount of IN718 alloy powder was premixed and introduced into H13 steel before forming. This increased the contents of nickel and chromium in the retained austenite during the forming process, lowered its martensitic transformation temperature, and effectively inhibited the formation of high-carbon martensite. The tensile test results show that the yield strength of the modified H13 steel is 1 176 MPa, the tensile strength is 1 615 MPa, and the elongation at break reaches 10.6% . The comprehensive performance is superior to that of existing laser-directed energy deposition methods for H13 steel. Microstructural analysis indicates that the austenite in the formed sample blocks is scattered and that there is an enrichment of nickel and chromium in the regions where the austenite is distributed. The scattered retained austenite can coordinate the deformation of the matrix and improve the uniformity of the internal deformation of the material. Moreover, the introduction of nickel and chromium effectively improves the stability of the retained austenite and delays the formation of high-carbon martensite.