Laser melting deposition technology has tremendous application prospects in the mold repair industry, and determining how the microstructure and mechanical properties of deposited parts vary with respect to the laser parameters is highly important for selecting the optimal mold repair process window. Experiments on laser melting deposition of H13 steel under different scanning speeds and laser powers were carried out, and the evolution of the microstructure and mechanical properties were analysed. The results show that as the scanning speed increases from 400 mm/min to 600 mm/min, the amount of fine martensite increases, the hardness of the deposited layer increases by approximately 3%, the plasticity decreases by approximately 1%, and the strength increases and then decreases. An increase in the number of defects leads to a decrease in the bonding strength with the substrate by approximately 20%. With increasing laser power from 1 800 W to 2 200 W, the size of the martensite increases, while the martensite content decreases. The hardness of the deposited layer decreases by approximately 5%, and the strength and plasticity increase by approximately 34% and 2%, respectively. At the same time, a decrease in the number of defects leads to an increase in the bond strength of approximately 58%.