E Lou Xuan 廅樓亘 is the earliest transcription of avalokiteśvara in Chinese Buddhist texts. The cause of its formation is still unknown to us. This paper examines the different words of E Lou Xuan 廅樓亘 in different editions and examines the different pronunciations of each word. In terms of the general rules of Sanskrit-Chinese transcription and the evolution of Indian language, my conclusion is that (1) 廅 corresponds to *av(a) and the final consonant [-p] of 廅 corresponds to -v-, because the position of articulation is the same; (2) 樓 corresponds to * lo-; (3) 亘 corresponds to *-śva(r) and the final nasal [-n] of 亘 corresponds to -r-, because in the underlying language the sound value of r and n is close. In short, I think the original form of 廅樓亘 is *av(a)...lo...śva(r). This form is closer to the Sanskrit word avalokiteśvara, which is seen in the later Sanskrit manuscripts than to avalokitasvara which is found in the earlier ones.
