Cao, whose name is Zhong, was born and died in an unknown year. He was born in Fufeng, Ping Ling, in the Eastern Han Dynasty, and was a doctor when Emperor Zhang was in the Han Dynasty. He is good at seal script, especially famous for creating hanging needles and hanging dew. Jin Weiheng's "Four-body Book Potential" said: "In junior high school, Cao was good at seal cutting, which was less different from Li Si, also known as goodness." Cao's seal cutting method was called "although it is a little different from Li's method, it is very subtle" in the northern Wei Dynasty's "Jiang Shi Lun Shu Biao". Liang Yuan 'ang's Book Review of Ancient and Modern Times in the Southern Dynasties said: "Cao Xi writes like a Tao and talks nonstop." In the Tang Dynasty's "Shu Gu An", it was said that Cao's "official works were famous all over the world." He also said: Cao Xi "good hanging needle dew, and then the World Bank." And its seal script and official script are listed as wonderful works. Zhang Huai's book review ranked Cao Xishu third, on an equal footing with Han Danchun and Liu Desheng. Cao left some books, which he wrote in pen.

The 21st volume of the reflection of Wei Chuan and Liu Shaochuan said:

Han Jian junior high school, Fufeng Cao and Si are not much different, and they also applaud. Han Danchun is a teacher, which is a bit wonderful. Dan Wei is inferior to spring.

Taiping Guang Ji, Shu Si and Cheng Miao have already gone down:

FuFeng cao, after * * *, I don't know its officer. He is good at seal cutting, but he is a little different from Li Si. He has met a teacher for some time. Liu Chen was appointed as Cai Yong * * *, and later as a corps commander. Be good at sealing and adopt the method of happiness. True straight father's inscription has been handed down from generation to generation, and the seal engraver is a teacher.

Cao (the year of birth and death is unknown) has made great achievements in calligraphy. Fufeng Pingling (now northwest of Weiyang, Shaanxi Province) was a doctor in the early days of its capital (76-84) and was good at architectural calligraphy. His method is slightly different from that of Li Si, and he is very particular. At that time, he was said to be good. Some scholars and calligraphers learn their own methods, including Cai Yong and Han Danchun. After the Tang dynasty, people attributed the method of hanging needles to Cao Xi, which is well-founded. Wei Zhengshi asked (240-249) that the ancient prose and seal script in the Three-body Stone Classic are sharp, that is, hanging needles is a method to achieve Han Chun effect, which originated from Cao Xi. Monuments in Han Dynasty, such as Zheng Jiyi Monument and Tang Gongfang Monument, are all used as hanging needles, while Kong Zhou Monument, Huashan Temple Monument and Qin Zhao Monument are all used as hanging needles. The seal script seen in the middle and late Eastern Han Dynasty has rarely seen the jade seal like the carved stone in the Qin Dynasty, with rich brushwork and lively structure. Among the famous artists, such as Cai Zhuan's seal script adopted the method of Lisi and Cao, Han Danchun and Wei Dangshu also studied under Cao, and Chun and Dan entered Wei from Han, all of which have the same name.

Hanging needles and hanging dew are originally descriptions of two kinds of vertical pens. The lower tip is vertical to the end, standing without receiving is called hanging needle, and standing without receiving is called hanging dew. During the Eastern Han Dynasty, some people exaggerated these two brushstrokes into seal script. Exaggerate the drooping strokes to make them as thin as hanging needles, which is called "hanging needle printing"; Make small dots at the end of drooping strokes, such as hanging morning dew, which is called "hanging dew print" It is said that Cao pioneered these two kinds of seal scripts. He is from Fufeng Ping Ling. Birth and death are unknown every year. He served as a doctor during the reign of Emperor Zhang of the Han Dynasty.

Jin Weiheng's "Four-body Calligraphy" says: "Cao is good at seal cutting, which is less different from (Li), also known as goodness." The book review of the Northern Wei Dynasty called Cao's seal cutting "unique". Liang Yuanang's Book Review of Ancient and Modern Times in the Southern Dynasties said: "Cao Xishu is as good as a Taoist." Zhang's Broken Book in the Tang Dynasty said: "Cao's seal cutting is world-famous." He also said, "Cao is good at hanging the needle and revealing it, and then the world will do it." Its seal script and official script are excellent. Zhang Huaiguan's book review ranked Cao Xishu third, on an equal footing with Han Danchun and Liu Desheng. Song monks dreamed that "eighteen bodies are also clouds": "hanging needles, hanging dew, being Cao". The person who hangs the needle mark is clumsy and has the edge of the needle. Those who hang seals play with books and chapters, saying that they are embellished like light dew. "Evaluation: Beyond Lisi, unique. Emperor Xuanzong of the Tang Dynasty called it "the famous official seal, especially the method of hanging the needle and showing the dew, which was later adopted by the world".