A soil-water coupled finite element analysis incorporating the macro-element method is carried out to investigate the consolidation effect of ultra-soft soils using the vacuum preloading method. SYS Cam-clay model is employed as the constitutive model. Taking the one-dimensional compression tests and in-situ vane shear tests into consideration, the soil parameters and initial values can be determined correspondingly. The calculation results show that there is a good accordance between the observational and numerical settlements, and the degree of consolidation after 90 days' application of the vacuum pressure is around 61% by predicting the long-term settlement. By reproducing the unconfined compression tests numerically, the undrained shear strength can be determined using the state variables.The variation of undrained shear strength at a depth of 1 meter at different stages of the vacuum preloading shows that the strength of ultra-soft soils increases gradually, which is also very close to the in-situ vane strength.