Abstract: Fractal geometry is a good method to describe the natural nonlinear phenomena quantitatively,and fractal dimension is a quant it ative parameter.The fractal geometry is applied to studying the fault systems in the southern part of the South China Sea.Results indicate that the spatial distribution of all faults in the southern part of the South China Sea is a distinct fractal set with selfOsimilarity in the nonOscale range of 25~250 km,and the fractal dimension(capacity dimensions),obtained by a box-counting method,interprets well the characteristics of the spatial distribution of faults.The fractal dimension of all faults in the study area is 1.6601,that of the NEOt rending faults 1.3875 and that of the NWOt rending faults 1.269 3.Showed by isoline maps of fractal dimensions,faults arrange symmetrically on two sides along the spreading axis of the Southwest Subbasin;the densities of spatial distribution of the NEOt rending faults and the N WOt rending faults supplement to each other,indicating the interOrest raint properties of these two groups of faults.At last,correlating the fractal charact eristics of the spatial distribution of faults with the evolution of the South China Sea and the distribution of basins bearing oil or gas,it is tried to find out the relationship between the fractal characteristics and evolution of the South China Sea and that between the fractal charact eristics and distribution of basins bearing oil or gas.