Abstract: Based on the field data measured from several projects of soft ground improvement in Shenzhen city,as well as the test data from a serial of tests of secondary compression on the soft clay,the behavior of consolidation and deformation of Shenzhen soft clay was studied and a method to estimate the post construction settlement and the equation to estimate the coefficient of secondary compression after the removal of surcharge are proposed.It was found that its coefficient of consolidation and compression index obtained from lab are close to that calculated from the field data.Surcharge can reduce the secondary settlement of a soft foundation by decreasing the coefficient of secondary compression and by delaying the occurrence of secondary compression.