Abstract: The surface of a hot-dip pure zinc coil had large zinc flower and bright defects.By means of chemical composition analysis,microstructure observation,glow spectrum test,surface roughness measurement and scanning electron microscope analysis,the defect and normal hot-dip pure zinc coil were campared,and causes of these defects were analyzed.The results showed that the main reason for the bright defect on the surface of hot-dip pure zinc aoil was the formation of mirror-like zinc flower on the surface,which had high reflectivity and were visually brighter than corrugated zinc flower.The main reason for the generation of large zinc flower defect on the surface of hot-dip pure zinc coil was that the roughness of the substrate was too low,resulting in fewer nucleation points,and the nucleation of liquid zinc on the surface of the substrate was non-uniform.The ratio of nucleation rate to grain growth rate was smaller during the crystallization of liquid zinc,resulting in larger zinc grains.Macroscopically,it was a large zinc flower defect.