Prefabricated vertical drainage plate (PVD)-vacuum preloading method is effective in improving the dredged slurries. However, during the operating process, a dense area (soil column) with a gradually decreasing radius from top to bottom would be generated around the PVD, delaying the soil consolidation rate. Aimed at it, this paper assumed that the soil column radius attenuates linearly with depth, and based on the assumption of equal strain, and the Hansbo,s consolidation theory, the consolidation equation considering the change of soil column radius with depth is deduced. At the same time, by calculating the equation above, the influences of the permeability coefficient, the radius of the soil column and the variation of the radius of the soil column along the depth on the soil consolidation rate were explored, and compared with the existing laboratory test data. The result shows that the smaller the permeability coefficient of the soil column, the slower the dissipation of pore water pressure, and the slower the consolidation rate. As the soil column radius gradually increases, the soil consolidation rate gradually decreases. The smaller the residual coefficient after the attenuation of the soil column radius, the greater the attenuation degree of the soil column radius along the depth, the smaller the influence on the soil consolidation in the weak area, and the faster the soil consolidation rate. In the case of considering the soil column radius attenuation with depth, the presented results are in good agreement with the experimental findings.