Abstract: Copper-based metal coatings were prepared on the surface of AlN ceramics by pulsed YAG lasers. The defects of the cladding layers were analyzed. It was also studied how to control the occurrence of defects in the cladding layers. The defects of the cladding samples were mainly the cracking of the ceramic substrate. Cladding formation incomplete, micro-cracks cracks and pores. The results show that by adjusting the heat input of the laser cladding, the integrity of the ceramic substrate can be ensured and the cladding layer can be well formed. The pre-heating before welding and slow cooling after welding can reduce the micro cracks and the formation probability of the pores. By optimizing the laser cladding process parameters and process methods, a good cladding layer can be formed, and a transition layer is formed between the AlN ceramic substrate and the copper-based metal cladding to form a good metallurgical bond.