Zhang Huaiguan was a calligrapher and calligrapher in the Tang Dynasty. Hailing (now Taizhou, Jiangsu) people. The activity was held in Kaiyuan (7 13-7 14), where Guan Hanlin offered sacrifices and Cao Jun, a government soldier, joined the army. Chen Si's Book Score in the Southern Song Dynasty called it good, correct, practical and cursive. I am very proud of my calligraphy, claiming that "integrity and deeds are comparable to (Heather) and Chu (Sui Liang), and the grass wants to go it alone for a hundred years." Without leaving any handwriting. Yi Shu, Shu Duan, Guan Shu, and Treatise on Medicine Stone are important works of calligraphy theory.
Zhang Huaiguan's works:
Zhang Huaiguan's calligraphy criticism works include Shu Duan, Zheng Yao Shi Lun, Guan Shu, Yi Shu, Forbidden Classics in Yutang, Ten Techniques of Using a Pen, Ji Shu, Liu Ti Lun and Characters Lun. He also wrote Broken Paintings, but it's a pity that he has been dead for a long time. Zhang Yanyuan's Famous Paintings of Past Dynasties in Tang Dynasty quoted some essays.