The southern Ordos Basin refers to the areas south of HuanxianYananPuxian and north of Xian. The Shanxi Formation and the Member 8 of Xiashihezi Formation are important gasbearing intervals. Based on the analyses on the direction of palaeowater current, the content of superstable heavy minerals and feldspars, it is concluded that six palaeowater systems were developed during the deposition of the Shanxi and Xiashihezi formations,which respectively corresponded to the six feldspar content subdivisions and six sedimentary facies. Six feldspar content subdivisions are ShibangouHuanxian, Pingliang, ChunhuaYaoxian, HanchengChengcheng, DaningWell Pu1, HuachiYongningThe types and distribution of sedimentary facies are analysed. During the deposition of Member 2 of Shanxi Formation， smallscaled deltas were developed，which were mainly distributed in Pingliang region of the south western area, ChunhuaYaoxian and HanchengChengcheng region of the south area. During the deposition of Member 1 of Shanxi Formation，the distribution of the delta was larger than that during the deposition of Member 2. The delta front was developed in YananDaning in the north area, while the lake size reduced. During the deposition of Member 8 of Xiashihezi Formation, the braided fluvial delta was developed and was widely distributed. Lacustrine facies was located in ZhenyuanHuanxianHuachiZhengning and DaningWell Ji1.It has been proved that the effective division of different water systems is favourable for the prediction of sedimentary facies belts distribution.