Among all the researches related to the Kinship of the Three in our history, The Truth of the Kinship of the Three According to the Book of I-Ching (The Truth for short) by Peng Xiao is an extremely important annotation version. Based on The Kinship of the Three According to the Book of I-Ching by Wei Bo-yang in Han Dynasty, The Truth aimed to integrate the natural laws with the alchemy by the philosophies of I-Ching, and explained the pot, medicine and heating according to the massive symbols and the image-number system of I-Ching. The study consists of two parts. First, Wei Bo-yang cited the discussions on alchemy practicing based on the image-number system of I-Ching in Han Dynasty, among which the Four Symbols of Yin and Yang, the Correspondence between the Moon Movement and the Sexagenary Cycle, and the Twelve Symbols Derived from Qian and Kun were the most influential. Peng Xiao further developed Wei’s research and inherited Wei’s image-number theory recorded in the Book of Alchemy. Besides, Peng believed that the key of cinnabar restoration was the lead and heat. He indicated that the foundation of alchemy was the pure Qi of the beginning of the world, and one could acquire the physique of pure Yang by practicing that Qi. He also cited the image-number system of I-Ching to shorten the heating duration of cinnabar restoration, which made it possible to become immortal. The Mirror Map attached in The Truth illustrated the alchemy practicing within the map of I-Ching, showing the alchemy methods by using pot, medicine and heating, which paved a new way among the annotation versions of Kinship of the Three in the history