Ou Yangxun had a deep friendship with Tang Gaozu, and was awarded the post of assistant middle school by Li Shimin, and was promoted to be a prince and a duke of Bohai. During this period, he co-authored The Gathering of Literature and Art.. His regular script has the reputation of "the supreme principle of regular script" and has been imitated by later generations. He also founded "Ou Yangxun Bading" calligraphy theory, and wrote a book, summarizing the formal skills and aesthetic requirements of calligraphy, such as brushwork, structure and composition, which is a valuable legacy of calligraphy theory, China.