The spangle size of the 55% Al-Zn-Si steel is affected by the composition of the zinc pot,the cooling capacity after plating,and the substrate. According to previous studies,the size of spangles can be reduced by increasing the cooling ability after plating,and by adding Ti in the zinc pot. However,these two methods cannot reduce the spangle size smaller than 1. 5 mm. Therefore,in this study,we have focused on the influence of substrates on the formation of spangles of 55% Al-Zn-Si steel by comparing and analyzing substrates with different surface roughness,composition,morphology,crystal orientation,and alloy layers. The spangle size of the 55% Al-Zn-Si steel is affected by the composition of the zinc pot, the cooling capacity after plating, and the substrate. According to previous studies, the size of spangles can be reduced by increasing the cooling ability after plating, and by adding Ti in the zinc pot. However, these two methods can not reduce the spangle size smaller than 1.5 mm. Therefore, in this study, we have focused on the influence of substrates on the formation of spangles of 55 % Al-Zn-Si steel by comparing and analyzing substrates with different surface roughness, composition, morphology, crystal orientation, and alloy layers.