The problems of bearing capacity, settlement and shear deformation occur when constructing a structure such as harbor, airport and bridge on soft ground of marine clay, silty clay or sandy soil. Various ground improvement methods are applied to obtain preceding settlement of soft ground and strength increase. In this study, to analyze the applicability of PBD method in deep soft ground, the compound drainage capacity test was operated in comparison with SD. As a result of the test, a minimum drainage capacity of drain material was estimated to be more than $10;cm^3/sec$ at a more than $400;kN/m^2$ and less than $5;cm^3/sec$ at a more than $500;kN/m^2$ confining pressure in case of single core PBD. In case of double core PBD, it was estimated to be more than $10;cm^3/sec$ at a more than $500;kN/m^2$ confining pressure.