Xu Shi, also known as Yin Zong, was born around the second year of the Liang Dynasty's Datong era (536) and passed away in the ninth year of the Tang Dynasty's Wude era (626), living to be over ninety years old. He was from Yixing, Changzhou (now Yixing, Jiangsu). Xu served the Chen Dynasty of the Southern Dynasties, initially as the Military Advisor to the Prince of Xincai and the Prefect of Yixing. After the fall of the Chen Dynasty, he served the Sui Dynasty, holding the position of Imperial Physician. In the first year of the Tang Dynasty's Wude era (618), he was appointed as a Cavalier Attendant-in-Ordinary.

Xu was renowned for his medical skills, particularly his mastery of pulse diagnosis, and his flexible and adaptable use of medications, not confined to a single method. In the mid-sixth century, he treated Empress Dowager Liu of the Chen Dynasty using a medicinal fumigation method. At the time, the Empress Dowager was suffering from a wind illness that left her unable to speak and with lockjaw, making it impossible for her to take medicine orally. Xu placed a decoction of Astragalus and Saposhnikovia Root beneath her bed, allowing the medicinal vapor to permeate her striae and interstice like smoke. That very night, the Empress Dowager regained her ability to speak, and as a result, Xu was appointed as the Prefect of Yixing.

In diagnosing illnesses, Xu placed great emphasis on pulse-taking to identify the root cause of diseases. He advocated for the precise matching of medicine to the illness, opposing the indiscriminate use of multiple drugs. He believed in using a single, potent medicine to directly target the ailment. Throughout his life, his approach to pulse diagnosis and medication was uniquely distinctive.