Shui Jing Zhu"(Notes For the "Water Scripture")is a famous ancient geographical dook written by Li Daoyuan in the beginning of the 6th century A.D..This book recorded the existence of "the South river" in Tarim Basin. Howeverthere are many different viewpoints to the "South river". Some resea-archers consider that the "South river" didn't exist, and others consider that the South river runs across the center of Taklimakan desert from west to east adn so on.According to the textual research on "Shui Jing Zhu" and comparing the image taken from the satellite with the results of archaeological studies, the author of this paper considers that the "South river" was not fabricated, it did exist in ancient time.The "South river" had two sources.One was the Ya-rkand river and the other was the Karakhash river. But in ancient time the Ka-rakhash river didn't flow north-eastward and join the Yulongkhash river as it does today.In ancient time, the karakhash river flowed north-west ward had joined the Yarcand river.Then the joined river flowed north-east ward and got the name "South river", decause it was roughly parallel to the Kashgar riverthe "North river" named by Li Dauyuan-keeping quite a distance. And then when the Yulongkhash river and Keriya river run across the Taklimakan desert north ward.it roughly paralleled the "North River" keeping quite a distance So it also got the name "South river". Final ly, a river branched from the "North river" at the north-Past extremity of Taklimakan dosert and flowed south-westward, it was another fragment of the "South river.