By means of the drilling coordinate,sand depth,seismic stratigraphic interpretation(top and bottom of the sand body), and other geologic information, multifractal method is applied to describe the distribution of sand body of Sanya Formation in Beijiao Sag of Qiongdongnan Basin based on the nonlinear theory. It is indicated that the C-A multifractal model can distinguish abnormal distribution of sand body and predict favorable zones. S-A multifractal model can extract weaker abnormal information due to its de-noising advantages, so the feature of the northwest-trending sand body, and the more fine partial information are identified. It is shown that the multifractal method is feasible to study sand body distribution comparing with the result by seismic method. It is concluded that S-A multifractal model can extract favorable zones on the basis of the C-A model for exploration and development of Beijiao Sag.