Cao Sugong's ink stick making technique is a traditional handmade technique for Chinese calligraphy and painting ink sticks. Cao Sugong's ink stick making technique has a long history of development, clear inheritance, and distinctive innovation. Compared with the scope of the ink making industry in China and even the world (mainly Japan, South Korea and East Asia), it has unique characteristics in history, region, technology, products, and modeling, and is a representative of contemporary Chinese and world ink stick making techniques. In addition to the functions of calligraphy and painting tools and handicrafts, its products also have historical, cultural, technological and economic value. Ink, as a traditional Chinese writing and painting tool, is an irreplaceable material carrier for the development of Chinese culture. The Chinese ink stick making technique was initially formed in the Spring and Autumn Period and the Warring States Period. After evolution, from the Song Dynasty to the middle and late Qing Dynasty, the Huizhou area of Anhui Province gradually became the main ink making center in China, forming a mature "Hui ink" production process system. In the middle and late Qing Dynasty, the "Hui ink" handicraft industry developed towards Shanghai, a new coastal economic and cultural center, forming the "Shanghai Hui ink" style and crafts. In the past 400 years, Cao Sugong is the only witness, practitioner, founder and leader who has inherited the late Ming Dynasty and opened the Qing Dynasty to the present. Cao Sugong began to make ink in the late Ming Dynasty. In the sixth year of Emperor Kangxi's reign (1667), he founded Cao Sugong Ink Shop in Yansi Town, She County, Anhui Province, the hometown of "Hui Ink". In the third year of Emperor Tongzhi's reign (1864), the ninth generation began to settle in Shanghai. During the Republic of China, it was passed down to thirteen generations. So far, Cao Sugong is the longest-lasting "Chinese time-honored brand" in the contemporary Chinese ink industry, and it is also the only representative and relic of "Haipai Hui Ink". Cao Sugong's ink stick making skills combine the strengths of various "Hui Ink" schools and form its own style. In the Qing Dynasty, it was selected as the "Imperial Ink" of the court, and was known as "Shezhou is the best ink in the world, and Cao's ink is the best ink in Shezhou". After moving to Shanghai, it integrated the Shanghai style of artistic expression, achieved a comprehensive breakthrough in craftsmanship, modeling, and techniques, and led the Shanghai "Haipai Hui Ink" schools. After the founding of the People's Republic of China, all Shanghai ink-making workshops were incorporated into the public-private partnership. Cao Sugong became the only representative of "Shanghai-style Hui ink". In the 1980s, Cao Sugong accepted the government's instructions to make a special national gift ink "Rainy Arashiyama". When the party and state leaders visited Japan and other countries, they chose this ink many times to present it to foreign heads of government and celebrities. It was praised by the Ministry of Foreign Affairs as "the best ink". Cao Sugong ink is not only the leading product in the mainstream market of domestic ink sticks, but also famous in Japan and popular at home and abroad. In the early 20th century, the "Tieshai Weng Calligraphy and Painting Treasure Ink" commissioned by Japan to be customized by Cao Sugong is still the first choice in the calligraphy and painting ink market. Since 1980, Cao Sugong has been invited by Japan's oldest ink-making enterprise "Gumeiyuan" to cooperate in the production of commemorative ink for the 400th anniversary celebration; and accepted a group of Japanese calligraphy artists and calligraphy groups to customize ink products, promoting the cultural and trade exchanges between China and foreign countries in the field of the four treasures of the study. In 2008, Cao Sugong ink sticks and ink sold for 4 million yuan, of which more than 5% were sold to Japan, South Korea, Hong Kong, Macao and Taiwan. In the same year, statistics from the China Calligraphy and Painting Association showed that Cao Sugong ink accounted for 42% of the market share of similar products in the country.