The academic circle of Chinese phonology has noted that the Chinese-translated Buddhist canons had become phonological research materials since Alexander von Staël-Holstein and Wang Rong Bao, beginning to verify the ancient sounds with the sort of materials in miscellaneous degrees. Whereas, the visibility of Chinese phonology in the Liao dynasty could be scarcely known because of the limitation of material deficiency. Thus, aiming to draw a time and spatial boundary, this article initially observes the life of the Liao monk CiXian and the era of his translating process via selecting the four Chinese Buddhist canons translated by CiXian and extracting the Chinese transliterations from the Sanskrit mantras as materials. Next in anticipation of scoping the appearance of phonological system of Chinese in the Liao dynasty of the 11th Century, the article would describe, arrange the rules of the transliterated sounds, further discuss the Chinese phonological features and ascertain the phonological system of Chinese by means of transliteration and reconstruction, then distinguish the phonological changes reflected by the system.