"Thin and hard" calligraphy, represented by Liu Gongquan. Liu Gongquan was born in Dali, Tang Daizong in the 13th year (AD 778)-Xian Tong, Tang Yizong in the 6th year (AD 865), at the age of 88. Jingzhao Huayuan (now Yaoxian County, Shaanxi Province) was born. The palace is a prince, so the deceased called it "Liu". He began to learn from Wang Xizhi, the brushwork of Ou Yangxun and Yan Zhenqing, and then set up his own family. The regular script written is beautiful and strong. Compared with Yan Ti, Liuzi is slightly thinner, so it is called "Yan Liu Jin Gu". Mu Zong asked Liu Gongquan how to use a pen, and Gong Quan replied: "Use a pen in your heart, and your mind is right." "Mu Gong changed his face and remonstrated with his pen. In the Song Dynasty, Zhu Zai said: "The public power official book has the best operation mode, but the grass can't. "Its method is based on beauty, but it is rich and famous in the world." He began to learn Wang Xizhi's brushwork, and later read the modern calligraphy, so he tried his best to change the right army method, learn from Yan Zhenqing, and assimilate his new ideas, so that his calligraphy avoided the tendency of horizontal and vertical, adopted a balanced and thin and hard approach, and steadily chased Wei Bei, making his brushwork simply beautiful, vigorous and tight. Many scholars in later generations took Liu Zi as a model. When I arrived in Zhao Ji, Song Huizong, I took my thin and hard style to the extreme. Su Shi, on the other hand, put forward his own artistic point of view in Sun Xin's poem "The Old Man Looking for a Pavilion", and clearly put forward the view that "short, long, fat and thin each have its own state", thinking that Zhao and he are both beautiful women, but their beautiful styles are different.