Abstract: This paper describes the application of element geochemistry- statistics method to sedimentary basin analysis.Over 300 samples of mudstone were systematically collected from the two fully cored wells (W3 and SN15 wells) of southern Songliao Basin, 11 main elemens and 16 trace elements were analyzed for each sample. After the geochemical data are computerized with the models of group analysis, relation analysis, regression analysis and Markov transition matrix, the authors applied these results to stratigraphic division, sedimentary cycle analysis and the study of sedimentary fades, the following are the conclusions: 1 .The green mudstone sequence, which is generally considered to be the upper unit of the fourth member of Quantou Group, should belong to the lower Qingshankou Group. 2.The interbeded red-green mudstones of Yaojia middle member should be interpreted as the sequence deposited in shallow lacustrine flat environment. 3.The results of stratigraphic division and sedimentary cycle analysis obtained from this method should be more reliable than those from well logging for the unique thick mudstone sequence. 4. Element geochemistry is a good way to study sedimentary facies, but some cares should be taken, such as the consideration of sedimentary derivation in the working area, the choice of multi-sedimentary facies only depending on a few elemental geochemical data. 5.The element geochemistry-statistics method can well enlarge the application scope of well debris.