This study is to understand how fluidity and natural features of Art Nouveau style are reflected in hair style of Art Nouveau age and Modem age and be a help to the trend analysis of hair style in the future. The study is conducted with the research on Art Nouveau expression in hair style and analysis of hair-show, trend presentation, documents related with hair style, TV drama, theses, journals and internet etc through advance research for Art Nouveau and Hair. The result of the analysis on Art Nouveau pattern in hair design is presented as below. First, it shows rounded, winding, flowing and thick-waved style of Art Nouveau pattern in modem long and short hair style. It also shows the beauty of long, bending and flexible lines, waving liveness and thin and slim lines and this is the Art Nouveau pattern that is also applied to other fields. In terms of decoration, it does not use tree vines, leaves and petals that are expressed in paintings of Art Nouveau age. Second, it shows natural up-style by lifting hair up with waved long hair that is one pattern of Art Nouveau and expresses hair style with feathers of birds, tree vines, leaves and petals etc for more decoration in animal pattern to make cute, romantic and elegant style in hair style.