Abstract: The principle of preloading consolidation method is that the foundation soil under the load actions(with an increasing total stress σ) can increase pore water drainage(i.e.,reducing the pore water pressure μ) and effective pressure σ'.This paper introduces the design and construction methods to conduct drainage consolidation treatment to soft clay of large areas by combining the preloading with the plastic drainage plate with engineering examples.This paper also analyzes the engineering monitoring results and shows that after preloading consolidation treatment,the bearing capacity of the saturated soft clay foundation has been greatly improved,the soil consolidation effect is obvious within the depth range of the plastic drainage plate,the settlement after construction is also greatly reduced,and the primary consolidation degree of the foundation soil in all regions has been up to over 90%in a few years.