During the deposition repair process, components made of the high crack-sensitive K424 Nickle-based high-temperature alloy are prone to cracking. This study utilized the low crack-sensitive GH4169 alloy to repair the K424 alloy and investigated the effect of substrate preheating on the cracking tendency of laser deposition repaired GH4169/K424 alloy. Numerical simulation of the repair process was conducted to explore the role of thermal/stress field evolution in crack formation. The simulation results indicate that preheating the substrate effectively reduces stress, with the most significant stress reduction observed parallel to the laser scanning direction, where compressive stress decreased by 10.5% and tensile stress by 26.7%. Experimental validation demonstrated the inhibitory effect of preheating on the cracking tendency of laser deposition repaired GH4169/K424 alloy. Preheating the substrate to 300?C significantly reduced the probability of crack formation, resulting in K424 high-temperature alloy repair specimens with only a few minor cracks.