Abstract: Laser cladding technology, as an advanced surface strengthening and repair technique, has been widely applied in aerospace, mechanical manufacturing, mining, and other fields. However, the rapid heating and cooling thermal characteristics during the cladding process can easily lead to defects such as cracks, pores, residual stresses, and compositional segregation in the coating, severely affecting its forming quality and service life. Heat treatment, as a key method for regulating the microstructure and properties of cladding coatings, including preheating of the substrate before cladding and post-cladding heat treatment processes, can effectively inhibit defect formation, optimize microstructure, and enhance overall performance. This paper systematically reviews the application effects of substrate preheating before cladding and post-cladding heat treatment processes in defect control, analyzes the technical characteristics and defect mitigation roles of heat treatment, and looks forward to the future development trends of heat treatment technology in the field of defect suppression for cladding coatings. It aims to provide theoretical reference and technical support for the preparation and application of high-performance cladding coatings.