The mechanism and conditions giving rise to cracking during multipass laps laser cladding are investigated by finite element analysis software. Numerical analysis, combined with experimental observations, is also utilized. Calculations reveal that tensile stress is brought inside the cladding layer, and is mostly concentrated at the boundary of the substrate and the bottom of the layer. Thus, a tendency to crack takes place perpendicular to the laser scanning direction. In addition, preheating improves the process by reducing the thermal stresses in the first cladding. After cladding the parts twice, the stress of the cladding layer is decreased more rapidly than the stress of the scanning direction. Cracking is formed at a certain angle to the scanning direction. The reliability and the accuracy of the model are experimentally verified.