Gong Yue, also known as Cao Zhang, is a famous royal calligrapher in the history of calligraphy in China. The Book of the Old Tang Dynasty said that Xuanzong was "good at temperament and good at writing eight points". Calligraphy is neat, clear and beautiful. It occupies a certain position in the calligraphy of the Tang Dynasty. Tang Dou Yi's Shu Shu Fu says: "Kaiyuan should be dry, smart, vigorous and magnificent. His thoughts are like a spring, and his pen is swallowing whales. " "Ancient and Modern Law Library" says: "Tang Huang Ming has eight chapters of grass in cm, which is rich and lush." There are many books handed down, the most famous of which are Fu on the Cormorant, Ming on Mount Ji and Shijing.