Yang Di acceded to the throne, and Ou Yangxun was the doctor too often. In the third year of Wude (620), he took refuge in Dou Jiande, the king of Xia, and was named Taichangqing. In the fifth year of Wude (622), he surrendered to Tang Gaozu Li Yuan and became a teacher. He moved to Guanglu, Yin Qing, where he became a doctor. He was given a bachelor's degree in Hong Wen Pavilion, conferred the title of Duke of Bohai, and presided over the compilation of the Collection of Arts and Literature. Zhenguan died at the age of eighty-five.
Ou Yangxun is proficient in calligraphy, and he is also called "the four outstanding figures in the early Tang Dynasty" with Yu Shinan, Chu Suiliang and Xue Qi. Because his son Ouyang Tong is good at calligraphy, the father and son are called "Big Europe". Calligraphy is in danger in Pingzhong, nicknamed "European style". Masterpieces: Regular script includes Jiuchenggong Li Quanming, Huangfu Birthday Monument, Huadu Temple Monument, and running script includes Zhong Nimeng's stickers and thousands of characters.
He has his own unique views on calligraphy, including eight methods of calligraphy works, teaching strategies and thirty-six methods of brushwork. Huadu Temple Buddhist Pagoda Inscription, Yugonggong Wenyanbo Inscription and Huangfushengchen Inscription are called "the first regular script in the Tang Dynasty".