In this study, the Ni-based-alloy coatings are prepared on 45 steel substrates by laser cladding with coaxial powder feeding. The fracture morphology analysis is conducted to evaluate the fracture mode and types of cracks. In addition, the energy-disperse spectroscopy is used to further investigate the mechanisms of crack initiation and propagation. Furthermore, the effects of the laser-cladding-process parameters on the cracking sensitivity are studied. The results show that the cracks in the Ni-based-alloy coatings are due to the quasi-cleavage fractures, which are a type of brittle fracture. Moreover, it is shown that the thermal residual stress causes the crack initiation at the interface and the subsequent crack propagation to the coating surface. It is further shown that the process parameters have significant impacts on the cracking sensitivity of the coating because the uneven distribution of the hard phase (including boride and carbide) and the brittle eutectic organization result in a high cracking sensitivity. Finally, the basic strategies for controlling cracks during laser cladding of Ni-based-alloy coatings are proposed.