Annan studied calligraphy, first Han Li, then two kings, and then the works of Yan Zhenqing, Liu Gongquan, Chu Suiliang, Zhi Yong, Huang Tingjian, Mi Fei, Su Dongpo, Zhao Mengfu and Wen Zhiming. He also praised outstanding contemporary calligraphers, especially Mao Zedong's calligraphy art, to learn from each other's strong points. His works are mainly regular script, running script and official script, especially good at cursive script and hand-rolling. Its regular script style adopts the method of Jin and Tang dynasties, which is easy to learn, rigorous in statutes, regular in structure, elegant and smart, and natural in writing. However, his calligraphy and cursive script are both rigid and flexible, writing smoothly, winning by risks, and emphasizing and highlighting the beauty of rhythm and harmony of calligraphy.