The calculation of the settlement after the soft foundation treatment is directly related to the unloading time of the soft foundation treatment. In order to study the post-construction settlement characteristics of soft foundation treatment under secondary consolidation, the numerical models of soft foundation without consideration of secondary consolidation and under secondary consolidation were established by MC (Mohr-Coulomb) constitutive and SSC(soft soil creep) constitutive construction, respectively, and the influencing factors of secondary consolidation were proposed. and the existing settlement calculation formula was modified, and the results showed that: (1) The secondary consolidation has a significant effect on the sedimentation rate, and the sub-consolidation is only about 0.5 times of the non-secondary consolidation sedimentation rate, and it is recommended that the sub-consolidation impact factor should be 0.5-0.8. (2) The sedimentation rate calculated by the method proposed in this paper is similar to the measured data and has good applicability.