Based on the Gibson large -strain consolidation equation, three assumption conditions of simplified equation are verified by the analysis of high pressure consolidation tests of dredged fill. Large-strain consolidation simplied settlement prediction method of double-layered soft clay foundation is proposed under step load, which be applied to the settlement process prediction of double-layered soft clay foundation of dredged fill and marine deposit silt in land reclamation projects. The obtained results verified that: 1) The relationship of void ratio e-effective stress and coefficient of permeability k-(1+e) of dredged fill is linear, and large-strain coefficient of consolidation of dredged fill is approximately constant under different consolidation pressure of 0-25 kPa and 25-200 kPa. 2) Compared with the classical consolidation theory, the consolidation settlement process of doublelayered soft clay foundation obtained by the large-strain consolidation simplified method is more reasonable, which provides a facility and practical settlement prediction method for soft clay foundation.