Based on an air spraying method, micro-WC-12 Co powder and nano-WC-12 Co powder were deposited on 45 steel respectively. Then the electrical contact strengthened equipment was used to remelt the coatings and the enhancement layers were formed on the substrate surface. The microstructure, hardness and thermal shock performance of the enhancement layers were investigated; The chemical composition and phase constitution of the enhancement layers were analyzed. The results show that the microstructure of enhancement lays are compact . And the enhancement layers poss high hardness and excellent thermal shock resistance. In the process of strengthening, the element diffusion in the interface shows that the metallurgic bonding is formed. Through compared with Micro-WC-12 Co Strengthening layer, nano-WC-12 Co strengthening layer has higher micro-hardness and more excellent thermal shock resistance.